if you want a powerhouse pc for cheep, then do look at Nforce (Duall chanel ram baby!), the only problem I ever had with my nforce chipset was getting ALSA to work, and that only took a day or 2 (and I learned SO much) although later I leaned that it would have taken me 10 mins if I had downloaded 'alsaconf'.
the nforce drivers put out by Nvidia do help by giving crappy sound (Which is why I replaced it with alsa) and they got my onboard NIC running. also people used to have problems with AGPgart, but that has been fixed in the kernel for a while, and slackware comes with the correct module compiled by default.
people are right, do stick with an NVIDIA vid card; SOOO much easier to install.
here is a nice biostar
M7NCG for $64, it uses M-ATX formfactor (Cheeper cases) and it suports up to the 400mhz fsb, I have a M7NC
D (its full ATX cousin) and I highly recomend that line.
and it has an onboard Gforce4.
then select an athlon or duron of your liking ($30-$200)
and 2 sticks of some cheep ram (30$ each)
then a case and PSU and you have your selfe a nice barebone system, add drives and peripherals (ie monitor, keyboard) and you have a nice computer for $400-$1000
EDIT:
I just noticed, without realizing it, everybody here automatically suggested an AMD based system, nobody has made mention of intel so far.