You need to get HL2, arguably the best game released to this date, best in my opinion anyways.
I found Doom 3 overrated and overhyped, I think people just got a bit excited since "OMG Doom is back!" and assumed it'd be good. The engine is the only thing that shines about that game, the gameplay is horrible in my opinion and I got bored of it once I got over the awe of the graphics.
Guild Wars and WoW are both good games, I prefer Guild Wars just because it's free and I like the gameplay better than WoW plus the graphics are pretty impressive for that type of game.