ati radeon 9200se help

i just upgraded my video card from an ati 128 pro 32mb to a ati radeon 9200se 128 mb. for some reason when i play UT2004(versus bots) i get lag. i didn't get lag before when i was using my rage 128. shouldn't the 9200se be better than my old video card? could it be a driver issue? help would be appreciated. o btw, i have a dimension 4500