You should never post a product key on a public forum like this.
Your product key will probably never work again because now any
shmuck with a bootleg copy of Office can use your product key to
activate their bootleg copy. Good job, genius. But as long as
you're at it, why don't you also post your credit card number,
expiration date, and security code here so that the whole world
can use those too?
If you are trying to install a full version of Office 2003, and
if the computer already has a trial version of Office 2003
installed on it, then you should: 1) uninstall the trial version
through Start | Control Panel | Add or Remove Programs, 2)
restart the computer, and 3) install the full version from the
Office 2003 CD. See
http://support.microsoft.com/?kbid=836178
"You receive an 'invalid product key' error message when you
start an Office 2003 program after you install Office
Professional Edition 2003" for more information.