Neil wrote:It means you are not using an OEM copy of Windows. The ThinkPad key will not work with Retail, Upgrade, Educational or anything other than OEM.

Thanks!

Just got a used T43 and the xp product key on the bottom doesn't work. Does that mean that it has expired?

This my first post and I love the forum! Just got a T43 that has Ubuntu installed......I have the XP Pro key and would prefer to run XP, however I don't have the install disc. What can I do?

Thanks