Just thought I'd pop my head in and recommend a couple of games.
First off, you've got to try Hitman: Blood Money. If you're into stealty games, this is for you. If you're into bam-bam-blood-and-guts, this is also for you! Each mission (just as in all of the hitman series) can be done a numerous amount of ways. You can go in guns blazing, or you can make your hit look like a complete accident. It's all up to you. Also includes a neat new feature that lets you customize some of your weapons. Scopes, laser pointers, silencers, armor-piercing rounds... Nifty stuff!
Secondly, try to get your hands on The Chronicles of Riddick: Escape from Butcher Bay. Not only does this game play and LOOK very good, but it's been overlooked plenty of times. I can play this game with maxed out graphical settings and it plays flawlessly. Absolutely beautiful game, in my opinion. As with Hitman, you can either hide in the shadows and wait for the ride time to jump out and slit your enemy's throat, or you can go in guns blazing. It has very nifty melee combat integration. If you're familiar with the Jedi Knight series, you'll get how it works; basically your punches and such are determined by the direction you're pressing as you attack. Works nicely, and gives a real nice feel to the world. For those who are familiar with the movies, this is a prequal to the Pitch Black movie. You get to experience all of Riddick's nifty little adventures and whatnot. Check it out.
Last but not least, an oldie but goodie... Thief II: The Metal Age. This is, for the most part, a complete stealth game. You have certain objectives you must complete, and you use your stealth to get them done. Hide in the shadows and creep in the hallways to get your business done. You could, however, just kill everyone with the arsenal that the game provides you with; a sword, a bow with several types of arrows, flashbombs, and other nifty gadgets. Try this one out. If you don't like it, it shouldn't matter too much -- I think you can grab this one really cheap at your local game store (if you can find it!)
So try these games out, have fun, and feel free to recommend some games to me.