Vista to XP

Hi,
I purchased a new dell E520 PC It had vista loaded when it came,
I want to use XP Home. I found out I could of had it come with XP on it
but I didn't see that part on the order form, dell don't want know only they would supply the XP Home Big deal/
I have found a new XP Home program which is on its way to me,
How big would this job for me to tackle or would it be better left to an expert.
I am a Intermediate with computers .

 

When you get the cd and when u put iy in your computer.. it might say "You have a latest version of windows" and might not let you... you might however put the cd in.. restart the computer. and when some says the pop-up "press any key to boot for cd..." do it and reformat everything.