Dell Server 2003- 25 CALs- one ADC- no Terminal Licensing Server?

I'm now overseeing a month-old DELL Windows 2003 Server Standard system that hosts an in-house database. Example - Office computer clicks a desktop icon which references the C: drive on that local machine. The GUI pops up and asks for a user name and pword which is checked against the server-hosted database software. The program then read and writes to the server-hosted database. This is a very small organization with maybe 15 individual PCs and one Server. No thin clients - all machines have HDs and Windows operating systems. The system was purchased with the initial 5 licenses for Server 2003 and 20 additional CALs, but no one installed Terminal Services or Terminal Licensing on this server. It is currently configured as a File Server (for automated backup purposes only), DNS Server, DHCP Server, and AD Server. No print server, no TS, no TLS. We have one Xerox WorkCentre 5030 which is not managed by any software on any machine, just plugged into the network. My questions are as follows - are the CAL licenses even necessary since each machine is individually licensed and is not viewing a GUI provided by the server? Wouldn't this clify just be an application server or even just a file server? Do DELL Server 2003 machines come pre-installed with the CAL licenses and that is why my predecessor never bothered with Terminal Services? Do I then need a separate machine to serve as a Terminal Licensing Server - does that machine require Server 2003 installed as well or can it run XP or Win2k, or even a linux solution? If it requires Server 2003 do I now need to purchase another Server 2003 license? What are the dangers of just running the Terminal Licensing services from the same server as the Active Domain? As you can see I'm stumped and need some help here - so thanks in advance!