The product key on your tower is for Windows, not Office. I am told the
product key for the TRIAL version of Office that is preinstalled on your
computer is on the sleeve for your Microsoft Works CDs.
Did you notice I capitalized TRIAL? There is a reason I did that - it is NOT
a permanent copy of Office. If you need/want Office, buy it. Uninstall that
trial version and install your full version to avoid a lot of potential
problems.
And lastly, I strongly suggest you invest in some sort of computer training.
I'm not saying this to be mean. If you don't know the difference between
Windows and Office, you are looking at a lot of headaches without training.