If you're willing to burn a hole through your wallet, pants, underwear, and skin then...
-A X4 processor would probably be better if you're keeping that computer for a long time. A Intel 3.2GHz Core i7 975 Extreme or AMD Phenom X4 940 depending on your motherboard. Intel reigns supreme regarding performance right now though.
-MSI Eclipse SLI Motherboard if you're using an i7 processor.
-Get a Nvidia Geforce GTX 295
-Seagate Barracuda 7200.11 1.5TB for capacity.
-Western Digital Velociraptor 300GB for performance.
-The Gateway XHD3000 is probably the best 30inch monitor you could get right now.
- For the cooler you could with a Thermalright Ultra-120 eXtreme.
- For the ram you could easily find great sticks at corsair, kingston, ocz, patriot, mushkin, crucial.
- Corsair HX1000W is a nice power supply.
and for the sound card, a X-Fi Titanium would suffice.
*If I had enough money I would buy that :-) but alas, only a person like me can dream of having PCs like these.