The Gigabit should still be able to run OS9... I would recommend 9.1 or 9.2 as the fastest and most stable and compatible. That being said, there really isnt any reason not to run OSX on it, as realistically the G4 will still leave the Pismo in a cloud of dust on that front (even my original Yikes G4 running a single G4/500 upgrade shreds strips off my Pismo, with PCI graphics to contend with and all), as 10.3 and later were progressively optimized to make use of the capabilities of the G4 processor and better graphics cards. I would recommend Panther updated to 10.3.9 as the fastest and at a compromise, the most compatible (currentish-softwarewise) variant of OSX on that machine... It will actually outperform OS9. If you are willing to take a bit of a speed hit then 10.4 is going to give you a much larger variety of useful software (TenFourFox to name just one of the many still-supported programs available that are only able to run on 10.4 or later) available to you.
As for displays, if you have an ADC port (looks similar to DVI but has rounded ends and different pinouts) then one of the smaller LCD Studio displays would fit the bill nicely... the G4-era ones are available in a 19" I believe, which your graphics card should support just fine, and these are fairly readily available and cheap, as they are useless on machines made from the late-2005 G5 onwards which no longer use ADC, that is unless you buy an adaptor which arent the cheapest things out (around 100 bucks from Hong Kong). If you have the ADC port which began in the G4's (I think the DA may have been the first with it), you are laughing! If you only have VGA to play with, the CRT Graphite studio displays are a beautiful unit, however they have a gargantuan footprint, and they are a little on the elderly side now and they are known for developing flyback snap which eventually ends in a failed flyback transformer and a screen that is basicallly a very heavy doorstop. I can guarantee however I will be using my 17" one on on my Yikes G4 until the bitter end, as I love it!
With regards to RAM, yes it is 168-pin double-sided PC-100 SD-RAM... make sure you do get the double-sided RAM or only half the capacity of the module will show up, and ensure it is PC-100 not PC-66 (this is fairly rare now anyway) as the bus speed is 100Mhz in the Gigabit machines and the RAM must be at least that fast. Brandwise, basically RAM is one of those items where you really do get what you pay for, and price is a fairly reasonable indication of quality. If the median price for a given price of module is say $45, and you find something supposedly equivalent for $15 brand new and shipped to your door, don't be tempted by the bargain price but rather let it serv as a warning to move along, as the RAM is likely to be poor quality rubbish made in a basement in china from substandard chips and in some cases won't work at all or will be faulty brand new out of the packet. So spend as much as you can afford to spend to get quality stuff... as a general rule of thumb, Corsair and Kingston RAM are always a safe bet and have made a name as reputable manufacturers over the years. As far as capacity goes, you can put in 4x512Mb modules in a GigaBit G4 meaning your RAM ceiling is 2Gb, which should be cheaply acheivable these days even with good parts.
Pertaining to hard drives, I wouldn't bother with SCSI... it is and always was a PITA for everyday use, and has quite a few limitations, the biggest one these days being individual drive capacity being capped at 36Gb. The last desktop Mac (as opposed to servers) to use it was the B+W G3 and that was basically a matter of them having bad IDE controllers that corrupted most IDE drives larger than 10Gb on the Rev.1 logic boards. The G4 uses a much faster primary ATA bus (ATA100) than the old beige clunkers of yore, and the capacity ceiling on the onboard ATA controllers is 130Gb, which in itself is more than you will ever fill on a G4 realistically (I havent filled 160Gb on my G5 and I have the 250Gb just sitting mostly empty), and you can install two internally on the inbuilt bus, or 3 very dodgily if you sacrifice the ZIP drive (I don't recommend this btw... not worth the hassles long-term such as mounting or CD-boot issues and premature drive failures from heat). You are probably going to be hard-pressed to find a SATA controller that will be supported by OS9 as the technology simply wasnt around in OS9's prime... by the time Apple even thought about putting SATA in a machine, OSX had been around for years and 9 was all but dead and buried. OSX might improve the odds but In any case, to be perfectly honest I would see installing a SATA adapter on that machine as being a bit of a waste of time, as the machine itself isnt really fast enough to see any major benefits from the increased drive sizes or higher speeds that are *theoretically* possible. In short, I'd save you money and a few headaches and buy a couple of 120Gb 7200RPM drives and leave it at that.
Lastly, regarding the machine-screws for the case plastics and handles, to my knowledge they are a proprietry screw and probably an oddball or uncommon thread, so it is unlikely that you will easily find replacements at any mainstream parts or fastener suppliers. Your best bet is likely to be just waiting until an case comes up for sale on CL or eBay, or a complete bashed up machine even that you can happily strip apart. the screws should be the same on all models at least prior to the Quicksilver... so basically you ought to be able to get any G3 B+W, or G4 Yikes, Sawtooth, Gigabit, or Digital Audio model case and use the screws in your G4. These machines come up dirt cheap nowadays as theyre 13-15 years old and well and truely obsolete... You should be able to pick one up for about $10-$50, or if your lucky you may get one free somewhere!
Anyway, hope some of this helped.
Kieran
As for displays, if you have an ADC port (looks similar to DVI but has rounded ends and different pinouts) then one of the smaller LCD Studio displays would fit the bill nicely... the G4-era ones are available in a 19" I believe, which your graphics card should support just fine, and these are fairly readily available and cheap, as they are useless on machines made from the late-2005 G5 onwards which no longer use ADC, that is unless you buy an adaptor which arent the cheapest things out (around 100 bucks from Hong Kong). If you have the ADC port which began in the G4's (I think the DA may have been the first with it), you are laughing! If you only have VGA to play with, the CRT Graphite studio displays are a beautiful unit, however they have a gargantuan footprint, and they are a little on the elderly side now and they are known for developing flyback snap which eventually ends in a failed flyback transformer and a screen that is basicallly a very heavy doorstop. I can guarantee however I will be using my 17" one on on my Yikes G4 until the bitter end, as I love it!
With regards to RAM, yes it is 168-pin double-sided PC-100 SD-RAM... make sure you do get the double-sided RAM or only half the capacity of the module will show up, and ensure it is PC-100 not PC-66 (this is fairly rare now anyway) as the bus speed is 100Mhz in the Gigabit machines and the RAM must be at least that fast. Brandwise, basically RAM is one of those items where you really do get what you pay for, and price is a fairly reasonable indication of quality. If the median price for a given price of module is say $45, and you find something supposedly equivalent for $15 brand new and shipped to your door, don't be tempted by the bargain price but rather let it serv as a warning to move along, as the RAM is likely to be poor quality rubbish made in a basement in china from substandard chips and in some cases won't work at all or will be faulty brand new out of the packet. So spend as much as you can afford to spend to get quality stuff... as a general rule of thumb, Corsair and Kingston RAM are always a safe bet and have made a name as reputable manufacturers over the years. As far as capacity goes, you can put in 4x512Mb modules in a GigaBit G4 meaning your RAM ceiling is 2Gb, which should be cheaply acheivable these days even with good parts.
Pertaining to hard drives, I wouldn't bother with SCSI... it is and always was a PITA for everyday use, and has quite a few limitations, the biggest one these days being individual drive capacity being capped at 36Gb. The last desktop Mac (as opposed to servers) to use it was the B+W G3 and that was basically a matter of them having bad IDE controllers that corrupted most IDE drives larger than 10Gb on the Rev.1 logic boards. The G4 uses a much faster primary ATA bus (ATA100) than the old beige clunkers of yore, and the capacity ceiling on the onboard ATA controllers is 130Gb, which in itself is more than you will ever fill on a G4 realistically (I havent filled 160Gb on my G5 and I have the 250Gb just sitting mostly empty), and you can install two internally on the inbuilt bus, or 3 very dodgily if you sacrifice the ZIP drive (I don't recommend this btw... not worth the hassles long-term such as mounting or CD-boot issues and premature drive failures from heat). You are probably going to be hard-pressed to find a SATA controller that will be supported by OS9 as the technology simply wasnt around in OS9's prime... by the time Apple even thought about putting SATA in a machine, OSX had been around for years and 9 was all but dead and buried. OSX might improve the odds but In any case, to be perfectly honest I would see installing a SATA adapter on that machine as being a bit of a waste of time, as the machine itself isnt really fast enough to see any major benefits from the increased drive sizes or higher speeds that are *theoretically* possible. In short, I'd save you money and a few headaches and buy a couple of 120Gb 7200RPM drives and leave it at that.
Lastly, regarding the machine-screws for the case plastics and handles, to my knowledge they are a proprietry screw and probably an oddball or uncommon thread, so it is unlikely that you will easily find replacements at any mainstream parts or fastener suppliers. Your best bet is likely to be just waiting until an case comes up for sale on CL or eBay, or a complete bashed up machine even that you can happily strip apart. the screws should be the same on all models at least prior to the Quicksilver... so basically you ought to be able to get any G3 B+W, or G4 Yikes, Sawtooth, Gigabit, or Digital Audio model case and use the screws in your G4. These machines come up dirt cheap nowadays as theyre 13-15 years old and well and truely obsolete... You should be able to pick one up for about $10-$50, or if your lucky you may get one free somewhere!
Anyway, hope some of this helped.
Kieran