I'm on genuine windows xp. to continue with microsoft word i am being asked for a product key no. how would i find the product key no. ? do i have to change from microsoft word to something else ?

The software could have been a trial preinstalled
if you have bought the office package the key is on the box
if you dont want to purchase microsoft office go to this link and download and install this free
open office, it is fully compatible with all microsoft office products such as word docs, excell, etc...
and has many cool other stuff

http://download.openoffice.org/index.html