A new and vastly improved 8800GTS 512 is coming out for $350, and will allow you to get speeds of the 8800GTX. You should be able to play Crysis on high, which is a
great game.The other option is the $240 8800GT, which gets 90% of the 8800GTX performance. Again should be good enough to play on high. ATI's 3870 is also a great option.
For RAM get at least 2GB of DDR2 800 from anything that gets good user reviews on Newegg. Something from Corsair or Kingston should be good enough.
New motherboards and processors are coming from Intel in two motnhs, so I don't know if you'd want to wait.
If you can't wait, I'd recommend E6850 by Intel. There are other options at lower prices like the E6750, the E6550 and so on. I'd recommend you buy the fastest you can afford from that series.
The only affordable quadcore from Intel is the Q6600. Unfortunately the clock speed on that is too low, and you are better off going for a higher clocked dual core like the E6850.
For the mobo I'd recommend the ASUS P5E3 Deluxe, though that is expensive. There are other options that are cheaper and will serve you well still.
