I have a 19 inch (2ms), a 22 inch (2ms) and a 24 inch (5ms) all Samsung's. There is a noticeable difference between 2ms and 5ms. Now whether it helps or hurts my game playing is another topic. I was using a 8800GTS 320mb video card with the 24 inch monitor with no problems. However, upgrading to a better system with a bigger video card did a lot for the monitor performance. But the 2ms vs 5ms difference is enough to recommend a smaller monitor over a larger rate monitor.
"Stick to a 22" because the native res will be 1680x1050 and that's not too high. 24" and we're getting into 1920x1200 and anything other than native looks blurry. 22" are really good value nowadays so you should look into buying one. Also you get the extra field of view now that 16:10 mode is fixed in AH."
One big consideration here is there is probably a $100 or more price jump between a 22inch and a 24 inch. Particularly if you factor in 2ms vs 5ms. To me the 22 inch just seems better. Your 7950 VC may be adequate on a 24 inch monitor but a 22 inch would probably perform better for you.
"If you get a constant 60 FPS on your 19", I don't think you'd need an upgrade for a 22". "
Big difference. Particularly if you go from a CRT to a flat panel. I play mostly offline games and web surfing on my 19 inch flat panel monitor. Its a good adequate monitor but the 22 inch flat panel is much better. I would say its a big difference.
I would suggest you look at the Samsung 22 inch 2ms monitor or a similar model. $250 at Newegg. There are plenty of cheaper models but not sure if they are worth it.