need advice on PC purchase please

It's about time for me to put together a new PC, so I'm trying to build one, mainly for crysis but any other DX10 games which come out in future. I originally started with a 3.6k build, but managed to scale it back without much of a performance loss to around 2.8k, and now found the same parts at a cheaper retailer, which are outlined below. (note prices are in australian dollars)

Video Card PCI-e (nV) 8800GTX 768MB Sparkle (575/1800GHz) 792.00

CPU/Processor Intel Core 2 Duo E6600 (2.40GHz) LGA775 439.00

Office PC Midi ATX Case ANTEC P180B Black No PSU 209.00

3.5" HDD SATA-300 Seagate 250GB 7200rpm 16MB (ST3250624AS) 105.00

Power Supply SilverStone ST65ZF 650w 187.00

Desktop DDR2 Ram Corsair-Performance 2GB (2x1024) 800MHz XMS2 TWINX2 MATCHED (TWIN2X2048-6400C4) 4-4-4-12 363.00

eVGA nFORCE 680i SLI Motherboard - Quad Core Support, 1066/1333 FSB, DDR2 533/667/800/1200MHz SLI Ready memory, PCI-E32X $397.10

So total comes to $2492.1

Now, if possible I would still like to reconfigure this and force the price down a bit more.

I'm wondering how many watts I would really need for this rig? Cause I can save a bit of cash with a less powerful PSU.

I'm also considering swapping the current motherboard for this one below, it saves $200, but not sure how they compare, I don't need the quad core support of my original choice:

Asus Mainboard P5B , Intel P965, Core2Duo support, Dual-Ch DDR2-800, PCI-E, FSB 1066MHz, 8-CH HD Audio CHK 3+ $198.54

And lastly, the graphics card seems rather cheap compared to other 8800's available. Anyone know whether it's a good quality card?

Thanks alot guys, and any other advice would be greatly appreciated.

hmm? well I was considering the P160, shaves another $40 off, don't wanna go too low, wouldn't want the thing overheating on me XD

What I'm really wondering about is the motherboard though, the 680i is rather expensive, $400, I'm thinking of going for an Asus P5B or Gigabyte 965p-DS3p but don't really know much about motherboards. Would they drag the rest of the system down or not? they kinda save me 200AUD

hmm? well I was considering the P160, shaves another $40 off, don't wanna go too low, wouldn't want the thing overheating on me XD

What I'm really wondering about is the motherboard though, the 680i is rather expensive, $400, I'm thinking of going for an Asus P5B or Gigabyte 965p-DS3p but don't really know much about motherboards. Would they drag the rest of the system down or not? they kinda save me 200AUD

DriftRS