How Many Installations Can I do

OK -- I bought a new W7 computer with Norton Internet Security 2011 (30 days free). I also have an XP machine. The salesperson said if I buy the Norton product -- the one that says 1 ueser, 1 PC -- then I can actually do 3 installations. I have 2 questions:

 

1) Is this true?

 

2) Even if true, wouldn't this be some kind of copyright violation. I mean, it is pretty clear on the box: 1 user/1 PC. But if Norton actually allows one to do 3 installations, then is it legal.

 

Also, if it is ok, can one do it on a W7 machines and an XP machine?

 

Mel