How can I depploy Office 2007 via GPO?

Hello
Iam trying to deploy office 2007 in server 2003 Ent environment, but when the installation completed and I tryed to open MS word it started installation then it toke long time then it asking me for product key. I used the computer configuration. There was no option to put the product key during the GPO creation. Is there anyway I can do this?

Thanks in Advance