All Athlon64 processors require PC3200 DDR RAM, so go from there. You might consider getting 2 RAM modules since all Athlon64 processors support dual channel memory. Stay away from the memory "kits". They are just 2 of the same memory modules at an inflated price. All you need is to buy 2 of the same modules.
I would strongly recommend getting an SATA drive over an IDE because SATA is faster (prices are about the same now).
As Albert indicated, you will probably not be able to beat the prices at Newegg, and, should you need it, their customer service is great. They also have a better selection than just about any other outfit.
You are apparently keeping your original graphics board. If it is an AGP card then your choice of motherboards will be extremely limited.
Edited by pascor22234, 20 June 2006 - 05:51 PM.