Proper way to upgrade to NIS 2010???

Hi

 

I am using NIS 2009 16.7.2.11 and am thinking about upgrading to NIS 2010.

 

There seems to be several options to do this -- download NRT and run this to remove NIS 2009 and then install NIS 2010

 

--or   just download NIS 2010 and let it overwrite/ remove NIS2009

 

Can someone from Symantec/Norton advise which is the best method.

 

My NIS 2009 is running great and I am trying to avoid problems going to NIS 2010.

 

I am using Vista Ultimate.

 

Thanks