IIRC from another forum, you need to save just about everything from a PC with XP, and then re-install and reload after installing Windows 7.
So on a new PC it may well make more sense to install Win 7 straight away, and start to live with it, rather than sticking with XP and then having to go through all that nausea at a later date.
Even more so, since most comments about Win 7 seem to be much more positive than they were about Vista at the time.
CJ