Is my power supply sufficient?

Instead of that get OCZ STEALTHXSTREAM 600W, its alot better

Yup, ditch the psu. Get a Tier1/2/3 one with around 500w:

http://www.tomswiki.com/page/Tiered+PSU+Listings?t=anon

The only other things I would swap out are the video card & cpu cooler.

8800GT is cheaper & faster. If you can wait a bit, the new 8800GTS 512MB should be out next week. It's delayed. Supposed to be out this week. It'll be somewhat faster than 8800GT. But the new reviews show the 8800GT takes the crown in terms of price/performance.

If you overclock, the Zalman will be loud at full blast. If you don't, it's whisper quiet. If you o/c, get a quieter cpu cooler like U120E, Geminii, Typhoon, Infinity, Ninja, Tuniq, etc.

I'd ditch OCZ that Maziar recommended and especially the Xion for something of better quality. SeaSonic, Corsair, Silverstone, PC Power and Cooling, and some Antec models would be the ones to look at. Something around 450-550W should be a good choice when it comes from a quality manufacturer.

Just bought a " Antec NeoPower 650 Blue". Thanks for the suggestions. I guess I already knew it wasn't of the best quality or sufficient. Just needed some confirmation. Thanks.

What I'd suggest is the Antex TruePower Trio I got, it's 650W and certified at SLIZone.com to run two 8800GTS' at once. So you'll be well safe and sound, without too much overkill on the price and power.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...