Contact Microsoft's Supplemental Parts team, they will replace the media for most products, or at least tell you your options. :)
They have a knowledge base article: http://support.microsoft.com/kb/326246
"How to replace Microsoft software or hardware, order service packs, and replace product manuals"
In the United States and Canada, you can reach the Microsoft Supplemental Parts team at the contact numbers that are listed here:
United States: (800) 360-7561, Monday through Friday, 5:00 A.M. to 7:00 P.M. Pacific Time.
Canada: (800) 933-4750, Monday through Friday, 5:00 A.M. to 7:00 P.M. Pacific Time.
TTY customers: Contact Microsoft at (800) 718-1599, Monday through Friday, 5:00 A.M. to 7:00 P.M. Pacific Time.
You can use that KB article to locate your local contact if outside North America.