I know this question sounds not useful when you just simply look at the documentation and find that 2003 isn't there.
But here is what happen, a client using AppMon 7.0 has installed host agent in quite a number of windows 2003 server, and found that it can monitor them. So their question is will they still be able to be monitor after upgrade in 7.2.
Given the documentation of 7.2 is of course the same as documentation of 7.0 (where you ctrl-F '2003' and will get nothing), I wonder how can I give them a definite answer.
We are only talking about host agent here, no code-level agent.
Host Agent in general is only gathering performance counters from OS so I don't think that there were any huge changes between Windows versions in this area (in compare to newer versions that are supported). I personally didn't check it so I cannot confirm but it sounds that is should work (even if it's not supported).