beebee......First .....I believe Norton only allows you to install NAV 2004 on one machine....however check the license to be sure.....Now that they are using the activation system ( this is to discourage buying one program and then loading it on several machines ) Did you activate the program when you loaded it on the second machine......Because if its not activated I dont believe you can get the updates......and in answer to your second query.......you should be able to receive updates right up until your subscription expires ...given you have activated it . You will receive messages remindinding you that your subscription will expire in so many days.
Hope this answers your questions......You can call Norton toll free and get further info.
Cheers
dl65