Is it worth it?

I administer a network of about 175 Win 2k and XP computers in an A/S 400 (I-Series) environment. We are not doing any windows updates since we do not have a windows server on the network (we are running Norton Corp on each desktop and updating from there).

Since all of my end-users are locked down as regular users in a local profile only, I do not know how to allow the updates to happen behind the scenes. I have considered installing an SUS server, but I wonder if it is really necessary to do the windows updates since that may create a network bandwidth issue.

I have not seen any major issues in three years. Is it only a matter of time?