how can i wipe everything from my computer apart from windows xp?

i have a Hanns-g computer which i have just got given back to me from a family member. He says he hasnt used the computer in a while so may need a few updates! im hopeless with technology and all i want to do is wipe everything from the computer but keep windows xp. Is there anyway i can do this i dont have the windows xp recovery cd nor blank discs to burn it on to until next week i just want it to start running properly because it is really slow. thanks for your help