Can anyone help me activate Norton 360 on my new computer?

Doh!

I have a new computer running Vista Home Premium.

I have a current subscription to Norton, and this allows me to run it on up to three computers.

I have access to the original product key.

Norton 360 is installed on the new computer, but only current for a brief period,

I have been fluffing around on the Norton site trying to figure out what to do to no avail...and the active subscription to Norton on this computer just timed out.

Dumb question, I know!