Since the iMac uses a small logicboard you can put it into a computer case and end up with a lot of extra room for cooling or you can crap it into a one of a kind object to use as a case.

Upgrading the CPU would be handy but it depends on what iMac you have. If it's the trayload iMac then yes the CPU is upgradeable. If it's a slot load imac then you're stuck. Also it's kinda hard to install tiger onto a G3 iMac, the system installer looks for Firewire and if the system doesn't have it it will not install. There are a few hacks and tweaks to bypass it though.

Also when you do install OSX make a 2 partition setup on the drive. Make the Primary 8GB. Make the second one the rest of the drive. For some reason if you use the whole partition on a iMac the system will act strange and some software will not install. Although this might be fixed in 10.3.x and 10.4.x (correct me if i'm wrong).

I've been trying to make my headless mac to work in a xbox case. I tried making a case out of legos but I don't have enough free time and I can't find my 5 gallon bucket of blocks, can only find my two buckets of special parts and road pieces.
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