Well when in an intense fight i've seen the framerate go as low as 22 frames per second, in a twitch based shooter like UT3 it almost guarantees you die. I've heard this game was coded very well and should ok even on bad hardware.
E2220@2.4GHz (can't oc dont ask)
Vista home premium.
wat settings are u running ur UT3 on?? try reducing them and check. If u cant overclock ur processor, how abt overclocking ur graphics card?? if u r at 22fps, it might make a big difference and make the game playable.. Also, u need 4GB ram to run vista premium so if u can get2gb more,it wud help.
PS.. i am not saying ur h/w is bad.. but its not great either
is this on-line or single player? and what resolution and settings are you running at? if its single player then the AI might be using a lot of cycles during intense firefights, if its multiplayer then your network might be being hammered during the same periods?