The 250 GTS can run crysis with veryhigh settings only in resolution up to 1280x720 after that is just not playable. In fact even the GTX275 cannot run crysis with veryhigh settings and 1680x1050.
i have evga 512mb 250 gts. with e4400 oced from 2.0 to 3.23
im using hp 22 inch LCD.
i can push all games to very high setting at this resolution 1680 - 1050( i believe)
except crysis, gta4 (may be more games that i didnt played)
in crysis, i setted very high, with 1680-1050 no AA. and im getting 25-30
if ur cpu is better than mine, you should be fine with 22"