Get key code from installed MS Office 2003 Professional

At work we have a CD set for MS Office 2003 with the key code for 10 stuck on one of the sleeves. When we moved the office around this CD set had disappeared. Is there a way to read the key code from one of the machines? or will I have to contact Microsoft to recover this code. We have a MSDN subscription and I can get the software but I will need the key code.

Thanks,

Steve C.