i was in your position about 6 months ago and i actually bought the amd64 3500 and its great. now i have the northridge one, and i know the winchester is out there too. i'm not toooo sure on the differences there, it might be the 90nm and 130nm i'd check with the cpu forum. but it is a great cpu.
if you're looking graphics card for gaming, don't go x700 pro! thats what i did. you don't get what you pay for at all for $200. if you're going to spend around $200 for a graphics card, get the Gigabyte 6600GT VP. aloooot better than the x700 for the same price.
this is my system and i spent about $1000 american.
AMD 64 3500 (939)
MSI RS480M2-IL (PCI-Express)motherboard
ATI Radeon X700 Pro 256mb vid card
1 gig (2x512) Corsair 400mhz ram (basically cheapest corsair ram i could get)
36gig 10,000rpm Western Digital Raptor
200gig SATA Western Digital hardrive
Good case with 4 led case fans and a 450w PSU
got all my stuff at monarch computer but ya i'd definitely check newegg. i would have gone their but i'm canadian and they don't ship to me