Good old Microsoft, I simply cannot understand how office worked for 2 years, the only reason why it would ask for a licence key is if it was in fact a trial version of office 2007 Installed by HP.
I wish you had not followed Microsoft`s advice, I would of told you there was a way to retrieve the licence key, and check if it was indeed a valid one for full use or a trail key. In any case Just forget office like said there are plenty of programs like open office that will do the same job as office 2007. And they are free.
Here is the link to open office aerowny, please click on the link bellow.http://www.openoffice.org/download/index.html?utm_expid=57643286-6&utm_referrer=http%3A%2F%2Fwww.openoffice.org%2F