Orlean, there's no set rules behind a "blanket license," so I can't say whether your TS CALs are covered under it or not. You'd have to check the details of that licensing agreement. It used to be, for Windows 2000, that W2K Pro included a CAL for connections to W2K term servers. That's not the case with W2K3 term servers: all CALs have to be purchased, even for XP clients.
As far as your question about memory, the overhead for a TS session is quite small, under 6mb, but that's when you leave out the shell. Depending on what the user is running and whether you have a program autoload for the session instead of using the Explorer shell, your memory requirements will be different.
For example, if I connect to a server using the explorer shell, it will load my profile, and the amount of memory my login uses will depend on how my profile is set up. On one terminal server explorer is taking up 21mb of memory and 19mb of virtual memory. On another server, I notice that my explorer shell is using on 9mb memory and 4mb virtual memory.
When I look at a server that currently has 35 active users all logged on to a custom application as a shell (no explorer) I see that each session's memory use runs between 12 and 22mb, with 17mb being about average. Since the application locks down the environment fairly well, there will be less fluctuation in session memory use than there would be if all the users were given access to the explorer shell, where they might copy stuff to the desktop, add extra background processes, etc.
Hope this gives you an idea how to guesstimate your needs.
ShackDaddy
