A good pc gamer before buy a game check system requirements if compatible with own hardware.
There are 2 nice sites that i recently discovered that make this job easy without spending too much time to look for them.
However for a full real test i suggest to see how the game really run with trying the demos.
Game-Debate provides a huge pc games database. Over an updated list of games there are useful features like search for them, info about release date (you can find on the list also games still not released). Once clicked on detail you can find the review of the game, genre, what platforms available, links (to software house, demo and patchs if available, etc…), video trailers, user comment with rating and system requirements both minimal and recommended.
With the service Can You Run It within an analysis of own computer done via browser (once selected the game from list or searched) you know if you can run the game.
Thanks to Instant Expert Analysis technology provided by System Requirements Labs within ActiveX/Java your hardware/software will be analyzed and then it will say if the game is compatible with your system.
Supported browsers are Internet Explorer and Firefox and supported O.S. are Windows XP, 2000, 2003, Vista and 7.