Product Key

I just bought a retail copy of
NIS 2007 I think this an old copy
of the product that may have been
on Sams Club's shelves since long
before Vista was released. Can I
download a newer version from the
Symantec download site and apply
my retail product key to it ?

I am just trying to end up with the latest build of NIS 2007 that I can.

Please help me to understand what to do.
Thanks Mike