I usually dont buy games- but when I buy one I make sure its good, I ask friends, look at reviews, make sure its worth the money etc...

The only games I own are:

Halo (pc) (I got this about 6 mos. ago)

TES 3: Morrowind (got that like... 2 years ago, and I might get Oblivion)

Starcraft + expansion (4 years ago)

Warcraft 3 + expansion (3 years ago)

and thats about it.