DONT go back to XP, a very very bad mistake. It first came out in 2001 so is now very old in computer terms.
It is also very vulnerable to computer attacks from viruses and malware. Later versions of Windows have improved a lot (under the covers) to become more secure and better able to recover from attacks.
Also all hardware in your PC requires drivers (to make them work) and it may well be that the hardware in your computer (if it is new) does not have XP drivers so certain hardware components will not work.
Also XP goes out of support soon so Microsoft will stop shipping updates and fixes for it, making it gradualy more and more likely to get attacked by hackers, viruses, malware and all sorts of nasties.
There are so many reasons why going back to XP from Windows 8 is a bad idea I cant believe anyone wants to do it.
It is like buying a new Ford Focus, decising you dont like it, and buying a Ford Anglia from the 1960s. Bad idea.
While I also dont like Windows 8, I dont recommend going back to any previous version of Windows, but if you feel you MUST go back then go back to Windows 7. That was probabgly the "best" release of Windows since XP, and is now a very secure and stable operating system which will be supported for many years.
But whatever you do, dont go back to XP.