I am currently useing FileMaker 4.0 on a NT network with 16 users. This fall I will need to upgrade to Server since I will be adding about 150 users. Can I just use Server or must I also buy the volume license to support my total number of users?

Here is the problem. To be compatible with FM 4.0, you will need server 3.0, which is no longer sold by FileMaker, Inc. If you already have 150 licenses for FM 4.0, you might be able to find a copy of FM 3.0 server on ebay. If you don't already own enough client licenses for FM 4.0, you will need to buy a site license package from FMI which will include FM Server 5.0 (or 5.5) and FM Client 5.0 (or 5.5). FM 4.0 checks for a valid license for each machine over the network and won't allow two copies with the same install code to operate at the same time.

You need to buy a volume license for your clients even with FM Server.

-bd