Q:
A: You just buy a copy of Win XP (but i don't think that retailers can sell it anymore),put it in your CD ROM drive, and it should prompt you to install XP. Follow the prompts. If you purchase a full version, you can do a fresh install of XP, but it will format/wipe/delete all data from your hard drive including windows and all programs (unless you save your data on a CD or floppy disk, make sure you know how to do this properly, or have someone that knows how to do it for you, "before upgrading or installing to XP"). I do not advise this unless you have all of your program disks and know how to re-install them.