That E6600 processor seems a little expensive... 400 dollars on newegg. Plus it seems to be consistently out of stock.
Asus Geforce 7900GT for 306.99$.
250GB Harddrive for 72.99$.
Sound Blaster Audigy 2 for only 64.00$.
That's all I have so far, still needs the case, RAM, CD drives, motherboard, and processor. But we're only up to about 450$ so far.