The build i have may be a bit too expensive or it could be dead on, you can always change things around to what your needs are.
i7 920 overclocked 3.80ghz, Ive never hit max CPU usage even streaming. it copes very well with games. deffo overclock it though if you go for this.
you can swap this out for an AMD FX 8350 4.0ghz(This cpu is also amazing)
Motherboard: i currently have a p6t deluxe v2 quite dated now but still is very fast and boots quickly.
Motherboard: personal i would want the Asus Sabertooth 990FX R2.0 Motherboard, reviews are very good.
PSU: go with something higher than you need so like a 750w corsair bronze will do the trick for future upgrades.
Heat-sink: Cooler Master Hyper 212 EVO looks like nearly everyone goes for as a stock replacement
you can build around that look for cases etc, depends if you want a totally custom build or pre built. pre built gaming PCs will be expensive though.