i don't know..i've been playing for ut for 3 years now. the fps i get at max quality at 1280x1024 and 1024x768 is the exact same. 100+fps constantly. it is easier to aim at 1024x768. yes you probably could change mouse sensitivity, but if you do that at higher resolution the accuracy would be less, because a higher mouse sensitivity would mean it would move faster, but, it would be harder for pinpoint aim. you could lower the sensitivity, but than it would be too slow. 1024x768 is a sweet spot for online gaming. im' sure if you spent the time changing your mouse sensitivity at 1280x1024 it could be the same.
Athlon XP 1.58GHz | MSI KT3 Ultra2 | 256MB DDR PC-3000 | GeForce 4 ti4200 64mb @ 310/533 | IBM 120GXP 40.0GB | Det. 41.09 | DX 9 RC2 | Win XP SP1