I would recommend the original Deus Ex and Vampire The Masquerade: Bloodlines. They're fairly dated and your computer should be able to run them.

Someone already mentioned Fallout, which I was going to recommend.

If you don't mind the dated graphics I would also mention System Shock. Bioshock which everyone rants about is somewhat of a successor to that game.

Voted "Biggest Waste Of Space" On The Bat-Boards For "Multiple Reasons"

Jerry Falwell On Rudolph The Red-Nosed Reindeer:
"Those hollywood, homosexual, jewish types making a show about a reindeer who is 'different' and just cant 'hide it'. Everyone knows if he tries hard enough he can convert himself to a normal, black-nosed reindeer."

I am 95% addicted to Porn. What about you?