Buying a desktop for gaming purpose?

I want to buy a desktop mainly for gaming purpose, but I don’t know much about the specifications required. All I know is that I need a good video card, and a decent processor. But regarding the processor, there’s core 2 duo or quad duo, or amd athlon some numbers x 2 or whatever terms that is appearing nowadays,... show more I want to buy a desktop mainly for gaming purpose, but I don’t know much about the specifications required. All I know is that I need a good video card, and a decent processor. But regarding the processor, there’s core 2 duo or quad duo, or amd athlon some numbers x 2 or whatever terms that is appearing nowadays, so I’m not too sure which is better.

Is anyone out there with knowledge or experience in this tells me what processor is most suitable, what video card is suitable, and any other things that are required for a gaming desktop? Things like power supply and so on.

And regarding the OS, is Vista good? From what I heard from my friends who are using Vista, and from my limited experience in using it, it’s quite slow, and caused the computer slower in all aspects, is that true? If I were to get a gaming PC, should I use XP instead of Vista?

And I’m not looking for a desktop for extreme gaming, but it should at least be able to play Call of Duty 4 on decent settings.
Update: And I don't mind to sacrifice a little on specs if I can save a lot. E.g. 2.5 Ghz and 2.4 Ghz's price differs a lot, let's say $500, then i would rather take 2.4ghz
Update 2: And if someone could explain to me, is a pentium 4 with 3.0 Ghz faster or a Core 2 Quad with 2.2 to 2.4 Ghz faster?
8 answers 8