What are the best specs for a gaming computer

2.2GHz+ Dual Core Recommended, 2GB ram minimum (4GB is recommended) and a good video card such as the ATI Radeon 5800 series. Usually other spec's are up-to-par if your computer meets the above standards; you just might want to consider a liquid cooling system if you using a laptop.

Operating system doesn't vary much, If you play modern games; I recommend Windows 7 but if not, try Windows XP. Just make sure you have the latest updates for whichever you choose.