Power requirements (new build)

Hello I'm new to these forums as well as building comps so I have a few questions. Come christmas I'm going to be buying my system and I'm not sure if I'm going to need an after market psu. Currently my planned build is going to be:

Intel Core 2 Duo E6750 (2.66Ghz 1333FSB)

EVGA 122-CK-NF63-TR LGA 775 NVIDIA nForce 680i SLI

RAIDMAX SMILODON ATX-612WB Black (/w 500w power supply)

G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400)

Western Digital Caviar SE16 WD3200AAKS 320GB 7200 RPM SATA

Lite-On Super-Multi LH20A1H

EVGA GeForce 8800 GT (512MB)

My case comes with a 500w power supply which I was going to use, but based on what I've been seeing it doesn't seem ample. Should I go with a cheaper case (w/o a psu) or should I go with this? Also, how does my setup look? Any recommendations/changes?

My thanks

Good day