Sounds like you put a second version of windows on your drive.
Back up everything you need then do a clean install by booting from the XP CD and select format the drive BEFORE installing windows. Guide click here
With windows loaded then you need to load antivirus and anti spyware and firewall
next the drivers for your motherboard and graphics card need to be installed either from a CD that came with the machine or download from the web (why you need antivirus and firewall first).