IMHO quad core is overkill. I have an AMD Opteron 148 & x800GTO2 and I have yet to come across a PC game I have been unable to run. Sure it's starting to show it's age with the lack of HDR or some newer features but the point is that going for something as extreme as quad core really isn't necessary if you want to game. Quad Cores are more useful for people who professionally video edit (I'm talking Adobe Premiere Pro here, not windows movie maker) and other processor intensive tasks, gaming relies more on the GPU so if you want to balance out the budget I'd spent more on the graphics card than the CPU.
Dual Cores are cheap as chips right now and will serve you well, my Opteron is only single core, not even overclocked and I've had no problems whatsoever. Don't let yourself get caught up too much in the PC building game, save the money for something else.
I'd recommend a decent AMD Dual Core, or the Intel equivalent (I hear Intel have the edge these days with the Core 2 Duo). And then look at getting a Radeon X series graphics card, something like an X1800XT or an X1900 should be able to keep up with the latest games out no problems.
Get a decent motherboard but don't go for the best if you don't plan to overclock, I'd say 1GB RAM at the minimum but you should really go for 2GB as memory prices have come down alot. PLEASE get a decent PSU (power supply) it's the number one thing people always skimp on, and regret later on down the line. If you have mid to top of the range stuff inside your PC you want a decent PSU that'll give you peace of mind.
If you need any more PC help I'd suggest http://www.overclockers.net/ tell 'em roughly what your after in their forum, and they'll give you a list of what to buy, give 'em a budget and they'll get it done for youJust be wary of what I said about getting pulled in, give them a lower figure than your willing to spend so that you can get value for money.
Good Luck, hope that helped. Oh btw, if there's one peripheral worth investing in, it's a nice monitor!
Got already a 21 " monitor, that should be enough
Tnx for the tips.
I dont need Quad Core, true, I should better spend my money on a kick ass graphics card