Should be easy enough, also XP comes with pretty well every driver you need for most things.
Windows Vista will probably be released later this year which as the replacement for XP might be worth waiting for, especially as official support for XP Home is due to finish at the end of this year - although on past evidence, this is likely to be extended.
Don't forget that you rarely get a complete copy of XP when you buy a bundled computer..just some recovery disks from the PC manufacturer. usually OK but I personally prefer having a proper copy of XP. That way I can rebuild the PC if I have to.