Considering price/performance.
E8400
R2094.40
http://www.prophecy.co.za/intel-core2-e8400-dual-core-30ghz-p-23787.html
or
Q6600 (G0 / SLACR stepping)
R2422.45
http://www.prophecy.co.za/intel-core2-quadro-q6600-bx80562q6600-slacr-stepping-p-23495.html
Both are awesome, you will regret neither, both OC well (when you get around to that).
The newer quads perform only a TINY bit better at the same frequency, indistinguishable in a real world scenario, and they cost more.
For the record / aka: my 2c:
Gigabyte GA-P35-DS3L
R1428.26 (not the cheapest from there, but their shipping is free over R1000 anyway, and they're great!)
http://www.prophecy.co.za/gigabyte-series-gap35ds3l-motherboard-p-23665.html
Vista 4GB DDR2 800 (2x 2GB)
XP 2GB DDR2 800 (1x 2GB)
(the cheapest decent quality ram, Hynix etc.)
8800GT
R2286.00
http://www.prophecy.co.za/inno3d-8800gt-512mb-overclocked-p-23492.html
Seagate 320GB 16mb cache 7200.10 Perpendicular
R698.09 (best price to volume ratio)
http://www.prophecy.co.za/seagate-barracuda-720010-st3320620as-320gb-sata2-7200rpm-p-2191.html
Omega iSonic Megapower 500W Modular Cabling (I've got it, it's solid, and cabling is oh-so-easy and neat)
http://www.prophecy.co.za/omega-isonic-megapower-500w-modular-cabling-fans-p-2288.html
Any case that takes your fancy and is decent quality. (I opt not to fork out over R1k for a case, just seems a waste)
Aw, I know dudes like their fancy mice, but I say just get a decent mouse-keyboard combo, optical 800dpi and higher.
Forget about the next iteration of MS OS, it will come when it does, in the mean time: Vista 64-bit or XP SP3.