Need help with windows xp

Ok… I might have installed the wrong driver for an Audigy SB card for my brothers computer. It said do you want to restart now? I clikced on the yes, i wish to restart now button. Now… When it tries to turn back on it just stays at the windows is loading screen for over 45 mins at time. I have tried repartition and reformat windows but it stil gives me the same problem. Need to know if anyone has had a problem remotly close to this one before and is willing to give some advice. ^^