This weekend I setup my home server in an old PC I had laying around. It was an uneventful install and everything just worked. I had to burn the disk a second time because it didn't write correctly.
Here is my hardware:
The motherboard is from an old HP Pavillion that I harvested parts from.
P4: 2.5ghz
512mg of RAM
Two old hard drives for a total of 120gig HD space
10/100 Network card built into motherboard