I want to replace the motherboard (and RAM and CPU, obviously), and use the rest of the system. It's in a regular ATX case, and I'd like to use my existing PS/2 KVM switch with it - so no USB keyboard or mouse, please.
Suggestions? How much will this run me? I want half a gig of RAM, at least. The CPU doesn't need to be the fastest available; I'll be happy with the best bang for the buck (which happens right at the knee of the price/performance curve).