I can second this. 2560x1600 is a huge jump from 1920x1200, totally worth the money. Even on FPS type games the response time is excellent unless you're really picky on that, in which case I'd recommend a CRT.
I say even the crappiest 30' monitor is better than the best 24' and smaller monitors and its not even close. 25x16 easily trumps any edges the smaller monitors may have in the way of response time or whatever. Once you play on a nice 30' display you'll never want to go back.