Can someone help me with this

client currently has an NT4 DC with a 2000 Terminal Server

They use the DC to log onto the Terminal Server

They are going to upgrade to 2003 server for the DC, the question I have is, are we going to need a licence for every user logging onto the domain, just to access the Terminal Server, or is it just for every user thats actually accessing resources on the DC?

Just want to make sure they order the right amount of licenses.