Windows Media Center Edition runs like crap

I recently installed WMC and it runs like crap. Whenever i scroll down a list it does the ghetto wave/section/not-fluent and pauses/breaks the window. I cant instal a critical update for it, i think becouse of SP 2 being intalled. any suggestions?

i didnt install WMC to use the actual media center stuff, Pro wouldent let me get on a flash drive. And now i lost the CD key for Pro. So I basicly screwed myself over.