Partitioning is best done BEFORE installing any OS or at the time the (XP) OS is being installed. XP "may" allow you to do so after the fact, if it does, understand that results vary. From your Menu open "Help and Support" and do a search on "Partions" and related subjects. DON'T do anything unless you're certain of the outcome. In any case and as a last resort be prepared for a COMPLETE re-install of the OS.