No software is linked to product keys.
As for the windows XP key you need to have an authentic one. "A buddy" of mine used a key from a keygen and it worked like it installed and everything but he couldn't get any updates (any microsoft autoupdates like security updates, IE updates and WMP). Microsoft.com also has a neat little feature where you can authenticate your key for US$199.99! Hehe that's actually brilliant IMO