Installation on Office XP Standard 2002

I had a trial version of office on my new HP laptop.
When the trial ended I bought the full version and
installed it. When I try to go to Outlook it gives me a
message telling me my trial version has ended and gives
me the option to convert now. I have already installed
the product on my laptop so when I follow the link to
convert now it won't accept the product key. Do I have
to uninstall the new office version and re-install using
the convert now option from the trial version or can I
fix this without doing that?