If I remember correctly, there is no 128 gig limit on these machines. There certainly isn't a hardware limitation, since I've used drives much larger than 128 gigs. Mac OS will either see a larger drive as 128 gigs or as full size - they've always been smart enough to not have the "wrap-around" problem.
The reason there's no hardware limit is because IDE transfers are done via software, so there's no hardware controller which would have to support ATA commands for accessing more than 28 bits' worth of sectors (2^9 bytes per sector giving 2^37 bytes total, or 128 GB). But even if the ROMs don't support drives larger than 128 gigs (I might guess that booting from a partition passed the 128 gig mark wouldn't work), the OS certainly could.
BTW - I always found it easier to format using a PowerMac. Also, it won't run anything older than 7.1.
Give it a try and let us know.
The reason there's no hardware limit is because IDE transfers are done via software, so there's no hardware controller which would have to support ATA commands for accessing more than 28 bits' worth of sectors (2^9 bytes per sector giving 2^37 bytes total, or 128 GB). But even if the ROMs don't support drives larger than 128 gigs (I might guess that booting from a partition passed the 128 gig mark wouldn't work), the OS certainly could.
BTW - I always found it easier to format using a PowerMac. Also, it won't run anything older than 7.1.
Give it a try and let us know.