Alright, let’s take a look here. Looks like you plan on overclocking which is good. Those DFI boards are GREAT for overclocking despite their crappy rep. The rep is for anything other than their lanparty boards.
Decent cookiecutter proc, should overclock pretty well for you.
Good thermal paste obviously (who doesn’t know that) and good HS/F. Glad you chose a big case because I’ve built a rigg with one of those for my buddy and that thing is HUGE!
I swear by g.skill, they are a great value brand. They don’t overclock too greatly, but their heatsinks are pretty good, so don’t be afraid to up the voltage a taad bit.
Good gpu, best crossfire card available to date. To crossfire a 4870 or 4870x2 is just a waste of money. With that x38 board you will be able to have yourself plenty of upgradability in the future.
As far as the PSU goes, I have no personal experience with that brand. For PSUs I tend to recomment only recommended brands only. There’s a good sticky on good brands in the forums here somewhere.
And the case… well… 900 is OK. If you’re puttin out that kind of money though you might as well just put in for a 1200 and get a case that is (no joke) 5 times better. FAR better looks, better cooling, better cable management, better fan control. It is just an AWESOME AWESOME case and haven’t worked with anything better than it.
OS… that’s your call but I hate vista myself lol. I know alot of the issues with gaming on Vista has been addressed, but it still takes up far too many resources in my opinion..