Ahhh, okay. I understand. Well, not being the biggest gamer, I'm really not sure. Many games these days have widescreen resolutions in addition to the regular 4:3. That's the main issue. I tested with Max Payne 2 because I knew it supported 1920x1200. I haven't checked HL2 because I rarely play it (I get sick after 5 minutes of playtime - seriously). Check the setup options in HL2. I think games usually show all possible resolutions for that game, and not the monitor. Aside from that, I don't think I can be of much help when it comes to games.

I think the thing you should be more concerned with is that, if you're a hardcore gamer, you won't be getting anywhere near the best FPS when playing at 1xx0x1200. I'm not hardcore at all, so I bump it up as high as it will go as long as it keeps it above ~30 FPS.