I stuffed a g3-400/1mb with 1GB of RAM, Radeon 7000 mac edition video, 40gb, 20gb, 6gb for OS 9.2.1/osx 10.3.9/dump drive) along with a SCSI card and a ATA/66 card in the B&W in my room. I have a g4-450/1mb, Radeon mac edition, 512MB RAM, 64 bit SCSI card with 9GB scsi HD , Matrox RTMAC video editing card, and 2 10 or 20GB HDs for OS 9 and osx 10.3.9 in that machine. Both machines are revision 2 IDE, the G4 has a DVD reader while the G3 has a 40x liteon cdrom drive. Nice cool running machines and you can still use all your old ADB stuff.