Now to the Operating System. My suggestion would be to download Windows 7RC and then buy the full version when it comes out. You should get the 64-bit version, but if that is too much of a chore, then go with Vista Prem. 64-bit.
Look at the graphs towards the bottom of that page, in general the output power from a power supply is not perfectly stable, the ripple is a measure of how stable it is, the lower the ripple the better, high ripple will look very spikey and jagged and has the potential to damage components because of the power fluctuations. If you look at the 12 volt rail for test 5 and CL2 it is very obvious. Good ripple suppression like that in high quality power supplies creates graphs that look like the ones on this page http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
How about a 4890 for a graphic card.faster than a gtx 260and even competes with gtx 285
Although for the price of the 4890, you can get the GTX275. And if you look at the benchmarks here on Toms you'll see that the GTX275 beats the 4890 more often than not.. But I would take a look at the benches of the games you play and chose the one that does the best on those games..