Windows XP question?

i have a situation.
I have 2 pc's with windows xp proffessional on them. I've lost the CD for one of them, this is the same pc that now has to be formatted.

I've heared that you cannot use the same windows xp cd on 2 machines.

1) Is there a way for me to get windows xp cd key from the doomed pc?

2) Can i then use my other windows xp cd with the retrevied cd key to reinstall windows?

Thanks.

I lost mine recently, if you click on the link it will scan your computer and give you the code.

http://pcsupport.about.com/cs/pctuto.../lostkey_2.htm

Could some gentle, loving Mod move this to the Hardware/Software sub-forum? I'll buy a candybar for the Mod who helps out ...

Dairy Milk, please.