Windows xp is outdated Microsoft don't support it anymore so why would you like it? and what OS you currently have?
Windows xp is out-dated, and isn't supported my Microsoft any more, which means it has developed serious vulnerabilities. It would be far better to install windows 7, that is if the hardware specifications can support it. If not, I personally recommend Unbuntu, or if the specs are quite low Lunbuntu. If Windows xp is still your only option, your computer manufacture will no longer will provide you with recovery media to reinstall, so you will have to look on the web for recovery media, or on a site like ebay for a disk.