I have an ADSL connection, I have Norton. I wanted to still use
Limewire, but I wanted to stop another user on my computer from using it. I tried to stop them from even accessing it, by locking it with a file lock program, but they just
reinstalled it again. I dont know the port Limewire uses, but is there some way I can block Limewire, to stop from one user using it, so also that I can only unblock it too, for when I need to use it?

Limewire ports can be changed so unless you block every port your not going to prevent it that way.

maybe setting up a user account with password might help, unless of course the person you speak of is permitted access to the computer.

I'v never tried it myself, but apparantly you can setup guest accounts with limited access in Windows XP.

No, but this user knows how to download it. So I dont know a way how to block it.