I am guessing that you want to connect to your 90 computers from the outside of your LAN, or in other words from the internet.
Problem is that your 2003 server has probably just one ip-adress, and then you can only have one remote connection open at the same time because all remote desktops wants to use port 3389.
There are workarounds to this problem.
1) you could forward new external ports (on your 2003 server) to forward to the the remote connection port (3389) on each of the 90 computers.
Ex
:13389 -> computer1:3389
:13390 -> computer2:3389
So if your user then from the internet want to connect to computer2 he would enter the adress:
:13390
2) If you have a specific service you want your users to use, then maybe it is easier to install the programs your users need directly at the 2003-server, and then let your users using remote desktop connection directly against your server. Each user will then get a desktop on your server and with normal access rights they will not be able to change (or even see) the admin stuff.
This second solution demands more licenses from Microsoft to work, but on the other hand you can have a lot of connections to your 2003 server without even open your proxy