I beta tested Vista, and I'm here to tell you it's a memory hog! Very beautiful (although very MACish) O/S. Spend your money where it counts, alot of fast RAM, I'd say at least 2GB. As for a processor, I'd go with the Core 2 Duo, and you dont have to spring for the most expensive model as I've seen mid range chips OC'd to 4+ GHz on air! Case wise any will do just make sure you've got room for air to flow, and forget about 80mm fans, find a case with 120mm, they spin slower, push more air and are much quieter. I'd wait till the DX10 cards come out although I'm sure they will be quite pricey, Quad SLI should be hitting the mainstream very soon (you can already get a Quad SLI XPS from Dell) And make damn sure you invest in a QUALITY power supply, I've seen so many people spend so much money on their system then skimp on the power supply, I cant stress how important a QUALITY power supply is on a high end system. Don't be fooled by total wattage claims, they are usually deceptive and don't tell you anything you need to know. Instead, go by the total AMPS rating for each respective voltage RAIL. For instance: Your +12V rail(s) are usually the best indicator of a great supply. You want high amps, preferably MORE than 20, much more if possible if your building a power user/gamer system/SLI/etc.
Even better are supplies with MULTIPLE +12V rails. This separates the loads and the noise and effects that comes back from the loads, so that, for instance, the CPU is more stable, especially when overclocking. There are even power supplies now with 4 +12V rails, but they aren't cheap. Get a 2 or 3 rail system if you can.
Absolutely INSIST on a supply that offers overvoltage, undervoltage, overcurrent/overload, overtemp, and short circuit protection.
Get Active Power Factor Correction if you can (APFC).
ALWAYS go to the manufacturer's website(s) (some have more than one site, maybe international AND local, look at both as you might glean more info that way) and read up on the specs. For instance, what is the HOLD TIME? How good is ripple current reduced (that will indicate how noisy the signal is, too).
