Hello EAH1,
As for looking up your Product Key from your Registration information, for many years now, Microsoft has not been allowed to do that. In compliance with legal rulings, when a user registers their product, Microsoft does not store the Product key information linked to any customer personal identifying information (such as Name, Address...so on). In other words, when registering a product, the Product key is stored in a different database from the other registration information, with no link between Product key and Owner.
The product key for your Office 2007 should be located in the documentation that was included with your computer. If you are unable to find the documentaion that contained the Product Key, the best I can do is direct you to the support doc "How to replace lost, broken, or missing Microsoft software or hardware" http://support.microsoft.com/kb/326246/en-us or to contact the company that issues you the Product key (in your case HP).
Sorry I couldn't be more help,
Darin Smith
WGA Forum Manager