Right now is a bad time

In the next year or two the Core i7s will come down in price. They kick ass, but the bad news is they need a whole different motherboard and ram.

Re:Chirpysniper

Make sure you get a big enough case if you want to fit a GX2. And a beefy PSU. And i dont think you can SLI two GX2s? As they are basically two cards each anyway?

4gb is fine. If you want 8gb get vista 64 bit (and not home basic)

Core2quads are cool but yeah most games wont use it to the fullest. personally i would just go for the highest end Core2duo you can find...

Well I would do it Different, I would go for the newest of the newest:

Intel Core i7 its unbeatable at the moment, I build 1 for a customer the other day...

He has:
DFI UT X58 Mainboard
Intel core i7 940 cpu
OCZ Tri-channel 6GB memory
2 XFX GTX-295's (which are replaseble for HD4870 x2 cause mainboard supports crossfirex as well as SLI)
Thermaltake thoughpower 1200w
3x WD Velociraptors 300gb
2x DVD Multi-writers
with a Thermalright ultra 120 extreme 1366rt cpu-coolingbloc with Arctic Silver 5 cooling paste

if needed I can post pictures here!

p.s. for the OC guys here... this mainboard with the 920cpu (2,6Ghz Stock) made 4.5Ghz with this coolingbloc and cause of the fact the i7 has hyperthreading on every core, Windows vista find that the i7 serie has 8 cores

no, it means it has 8 logical CPUs, not 8 cores, strictly speaking.
And 6gb of RAM? why?

The core i7s are good but very expensive atm.

well it could be 3,6 or 12gb seeing the mainboard supports tripple channel

and you are right about the 8 logical cpu's, but funny that it shows