[Felix12g]

I'd advise going with a Thermaltake 650w power supply, they make very good hardware. If you're looking to go with SLI I'd even suggest grabbing a 700w. It looks like you're building a top of the line computer so a couple more optional things.
First I'd go with the best dual core you can handle financially. There's nothing really wrong with the one you've got but 6 months down the road you might kick yourself for that extra boost.
Second you might want to check out a raptor drive. They cost more than normal SATA drives but their speed is worth it. I picked up a 74 gig that I use to throw my OS and some other programs that can eat up CPU like photoshop, audition and 3DS Max, most games and other things that eat up storage I leave on the secondary drive.
Third the motherboard. I don't know how prone you are to try overclocking but the 680i has alot of potential to keep your hardware viable as a gaming platform farther down the road. I picked up one from EVGA and it works beautifully.

Good luck with Vista. You might want to keep your old OS install sitting around just in case. Some people like it, others hate it. You're going to have the hardware to run it, so like I said, good luck.