safe to download NIS to netbook?

I just bought a netbook and wondered if it's safe to sign onto internet on netbook (with no antivirus active) in order to download NIS per instructions I read about on this board.  My concern is that my netbook could pick up a virus before I have a chance to run Live Update.  Is there a way to download NIS onto a flash drive and install it on netbook, put in product key and immediately run Live Update?  Or am I being overprotective? 

 

 Also, I found NIS box for 2007 with product key.  Does it stay the same as long as you keep renewing or do I need to dig through my files to find a more recent product key.  Thanks for any help you can give.