new build, need some advice

Sometime in December I'm planning on building a new PC. I've upgraded my 5 year old Dell as much as I can without just wasting money stupidly and it's time for a new system.

Thermaltake Armor Series full tower case
Asus P5B Deluxe/WiFi-AP socket T intel p965 chipset
Intel Core 2 Duo E6600 (planning to overclock to 3 Ghz)
2 GB (2x1 GB) Corsair XMS2 DDR2-800
500 GB Raid 0 (2x250 GB) Western Digital SATA
Hiper Modular Type-R 580W sli ready power supply
Zalman CNPS9500 with the blue LED

I'm planning on keeping my sound card (X-Fi Music) and DVD burners from my current computer. I just got a new 20.1" LCD monitor yesterday (Samsung 204B) that runs at 1600x1200. I'm planning on using this next computer for mostly gaming so I want games to run smooth at this resolution. Games I'm planning on getting are Crysis, UT 2007, and maybe Gears of War if it's out for PCs.

Which graphics card should I get? The 8800 GTX is pretty damn expensive at $650, and the 8800 GTS is $150 cheaper. Would I be able to run those games at decent frames at 1600x1200 with just the GTS or should I go balls out and get the GTX? Also I'm not planning on doing SLI, it's too expensive.

Other questions:
Is that power supply enough for all the things in that system?
Can I OC the E6600 to 3 Ghz without a problem with a good heatsink like the Zalman I chose?

any input would be appreciated