Typically I just use a program like Speccy (
link) or CPU-Z (
link) to get a quick lowdown on what's inside a machine. Just download and run either of those (or both if you want to compare) and you should get all the info you'll need.
The only thing to be aware of is when games mention specific processors or video cards it doesnt mean that you need that exact one to run the games, just something that's comparable, for example an AMD phenom ii x4 is comparable to the Intel Core i3 processor.
If in doubt post the information you get here and one of us can tell you if it's good enough for you to run that game.