Does activating the NIS 2009 Product key cancel the 90 day trial period?

Hi guys, I have just got a new HP laptop that came with a 90 day trial Norton internet security 2009 pre installed. Today I went out to purchase the full version, but there is still 60 days of 'subscription' left. I would like to know whether If i activate my product key now, will it cancel out the trial or allow me to 'stack up' the remaining 60 days in addition to the other 365 days

Thanks

 

Andrew