I run several older games (Papyrus Nascar Racing, Grand Prix Legends, older versions of Sim City, etc.) on my widescreen and haven't had any problems. IIRC Grand Prix Legends defaults to 800x600 but fills the screen on my computer. I even installed an old Jack Nicolas (sp) DOS game on my machine and it filled the screen but the graphics looked so bad I took it off (I think it defaulted to 640x480 res). If the game doesn't include widescreen resolutions you can control how the monitor handles various graphic settings in your video card set-up but, I found that I couldn't using a VGA cable. I needed to use a DVI cable so make sure you buy one if it doesn't come with the monitor.
I've got a 22" LG (2ms response) that I've been very happy with. I run at native 1680x1050.