Your mobo will accept northwood & prescott designs
the ram is dependant on the FSB of the CPU
If you get a 533fsb CPU then pc2700(333ddr) ram
If you get a 800fsb CPU then pc2300(400ddr) ram
The higherthe number the better so if can go 800fsb not much price difference between them now..
Prescotts use more power and produce a little more heat
I would surgest a 400w + PSU and higher if you get lastest gfx as need extra power...
80gb would be fine unless you do a lot of d/loading (BB) or video editing