I picked up a Power Macintosh G4 and it has ATI Rage 128 Pro with 16 MB of VRAM
AGP 2x, and everythin except a hard drive. I read that to get it to boot from one site i need the original HDD, but thats not possible for me to attain. Something about matching numbers with the actual units numbers for OS or something? But, in another site I read that I can format any HDD to a Mac format and that will work up to around 80 GB and be able to boot to OS. The original was a 20GB. i do have an Emac and I made a bootable image on an external HDD drive from that using software, and the G4 Power Mac(tower) recognizes it, Im just wondering if I can format an 80Gb spare IDE internal drive to a Mac Format and use that when I boot the OS from the external drive which has the image. Its a "sawtooth" 400Mhz/1M Cache/128MB Pro SDRAM/20 GB/DVD-ROM/ZIP/56K MDM/KB somebody has upgraded RAM to 384 MB (256MB apple G4 PC100 + a 128MB PC100 Samsung chip), it is just missing that 20GB HDD.

 

I've dumped a 64 GB SSD in me iBook G4 and just dumped a burnt copy of Mac OS X 10.5 in it.
Works perfectly fine.

It's just a harddrive, you can swap those out.