MS Office XP cd&key

Hello,

could you take a position on this, please?

I have a (legal) product key to MS Office XP Pro, but my installation cd got phisically damaged and I had to borrow one from a friend.
At time of installation Office XP approves the key, but unfortunately after starting for instance Word 2002 for the fist time it says that the product key is invalid or one of 25-digits is missing.

Have both the installation cd and the product key to be from the same retail package?

Do you have an idea what could get wrong with it?

TIA,

ralfska