[Solved] Relationship between monitor and videocard and resolutions

In general a bigger screen will require a more powerful video card due the increased number of pixels being controlled and the resulting increase in graphics data to be processed. You are correct that lower end or older graphics cards may not be able to handle running newer games on larger monitors. For example, if you had say an HD4670 or a 9600GT you could probably comfortably run nearly every currently available game on resolutions up to 1280x1024 and probably some older titles at even higher resolutions. If you were to buy a 22" monitor and run a 1680x1050 resolution you would likely find that you would need to upgrade your card to achieve satisfactory framerates on newer games (older games would likely still be fine).

As for your question on the 8800GT versus the GTX260, and 8800GT is probably borderline for a 1680x1050 resolution on the newest games. It can probably still handle that resolution on 95% of the games out there, but likely will struggle with the newer stuff. Pretty much the same thing can be said for any card that is over a year old. A GTX260 should be able to comfortably handle pretty much any game at 1680x1050 (except possibly for Crysis, but that game sucks anyways) and can do most at 1920x1200 without much trouble. It would definitely be overkill on a 19" monitor.

Now, if you're trying to make a decision on whether to buy a new monitor or a new video card I'd recommend that you buy the monitor. Video card prices are much more volatile than monitor prices and you will likely see the video card prices drop substantially in a few months when the new models start to appear, whereas monitor prices likely won't change appreciably.