[Arkan]

For a processor, get the AMD Athlon XP. They run like hell for a great price. About the only drawback that i know of is they tend to run on the hot side. Just make sure you have ample cooling and you should be trouble free. Also, the AMD's need a decent power supply so don't neglect this area. I have an AMD Athlon XP 1400 and never had any trouble with it and as a matter of fact, i'm upgrading my second machine with either the 1800, or 2000 XP. So for you i recommend:

Athlon XP 1800
ASUS A7V333 Mobo
PC2100 DDR Memory (at least 256Mb)
Enermax 300W or 350W power supply