it sounds like it is an OEM cd-key

My laptops XP edition does not need a key to install because it is bios locked to HP I beleive.

I have the cd-key glued to the bottom anyways.

You should use your original key for the xp home. I beleive that you will be able to use it on your laptop and desktop legally as in the EULA.

someone correct me if i'm wrong