Well....Being as this is just a informational question..
(and of course you are just curious as to IF it could be done).
The official and correct answer is that you must have purchased a copy of WinXP for Each seperate 'puter you install it on.
[BTW, Don't hold your breath on ANY discount from MS]
Supposidly
, If your 2 computers are Identical (Same exact system, hardware configuration, memory, LAN card, etc) then the activation is supposed to be the same for a given hardware configuration.
I have even seen (although it was NOT HERE at ex-perience.com) at another WinXP site a step by step method for taking an XP home version of XP and converting it to a <cough> different version which does not <cough> have the 30 day restriction <cough, cough>.
Course I don't <cough> condone any such "messing" with your beloved XP files.
Damn Dust in the air <cough, cough>
Hey, but on a Brighter note
you could always check out some nifty sites that could actually help you <cough> keep your 'puter in top shape !!
http://www.winxptop.com/winxptop/default.asp
Don't say I never gave you nothin
<cough, cough>