Help help help with laptop

[savageman25]

Ive got an IBM think pad laptop with windows xp on it, for a few days now its been getting really slow and kept coming up with 'infected file' warning, that id send to the virus vault, to find it was a trojan in 'documents and settings', tried everything to get rid of them as i had 118 of them and couldnt do it, went to use it yesterday, and it took about 20 minutes just to let me sign in, it usually takes about 3-4 minutes from turning it on to getting to my documnets, adter 45 minutes! it eventually loaded my desktop, but as soon as i click anything it just freezes and then after abotu 20 minutes the screen goes blank and i cant do anything.
I was jsut wondering what i can do, as i dont have an xp disk and wanted to no if its possible to wipe the hardrive or what ever it is to reset it all????