terminal services is the mmc that monitors and control remote management. It might not be installed by ddefault but it can be easily added using inside "Add/Remove Programs" the section "Add/Remove Windows Components"
Only problem is that it is only in server versions.
Anyhow, Remote sesion (or remote Access) in Windows XP is not more than an updated version of terminal server (access), and of course it uses the same services, knowing this will give you several tools to monitored it, in the performance monitor you can use it to monitor many things about the terminal services and sesions.
To know more, you could also search inside Technet "The Script Guys" to see if they have a terminal services or remote desktop wmi script.