NIS and dynamic IP conflict

I have a wireless laptop that I have been trying to set up in a network with
my desktop and printer. I know this isn't rocket science, but I have been
having problems. I have Norton INternet Security and it keeps blocking
access to the desktop. What I have done to remedy this is to go into NIS
and add the IP of the laptop as friendly. But my laptop is set to dymanic
IP addressing and every time it goes dormant I am blocked from access to my
desktop again. I am thinking I need to set a static IP on the laptop and
add it to NIS. If this is the best way to handle this, how do I do this?
And if not, what do you suggest?

Thanks,
Deborah