If you can get a hold of a Windows XP operating system, one of the options when installing it is to reformat (wipe out) the hard drive, so you shouldn't pay anybody to do that. All operating system installs give you that option. You should find a way to grab any important files like photos, .mp3s first. The OS comes with some version of Internet explorer, and you can always download Firefox. I would worry about the Office software next. The biggest issue with installing the operating system is online verification with Microsoft. They can tell if it's already been installed on another computer and that will block the install.