xp over vista

OK, I haveAcer Aspire 3680 to repair from customer,upgradet with vista basic.The customer doesnt want vista anymore so he want good old XP.Q:Is there some problem with reformating,I must be aware?Cos I've heard thatvista will not let to be reformated with other lower OS.Give me step by step reformating Vista with XP.
Studio T,do you remember this thread:http://forums.majorgeeks.com/showthread.php?t=123629
Well,he repair the laptop,in ACER, they switch the hard disk(he don't want to tell me the ammount of money for the repair, but I can gess with P&P how much money is this).

 

Cool, thanks Halo for the tip.SPEEDY HALO!!!!