You need to BUY an actual copy of Windows XP for Home or Professional. Then create a slipstream for SP3 if you want a XP SP3 disc. Its illegal to download Windows XP ISO's from torrents, however another option is if you have a genuine key you could always borrow a friends OEM disc of the proper version of XP to perform installation and use YOUR KEY NOT THEIRS if you don't want to buy a disc.