First, You need to examine the Product Key carefully. It is a common error to mistake a "B" for an "8," a "G" for a "6," an "S" for a "5," or a "Q" for a "0" or "O." Also, be sure that your CapsLock is off while entering the Product Key. If this does not solve your issue, continue below.
Microsoft has an article (link below) informing of how to contact them for help with the following issues:
* Replace lost, broken, damaged or defective Microsoft software disks.
* Purchase product upgrades.
* Replace broken or defective Microsoft hardware products.
* Check the status on support orders.
* Order downloadable service packs.
* Replace missing manuals.
http://support.microsoft.com/kb/326246
Related information:
http://support.microsoft.com/default.aspx?scid=kb;en-us;310637