If you haven't yet setup terminal services, you will go
into Add/Remove Programs, then Windows Components, Near
the bottom is Terminal Server, you don't need the
Terminal Server licensing. You will hit next, it will
ask you Application Mode or Admin mode, you will want the
admin mode. Once this is going, you should be all set,
you can use the Windows XP Remote Desktop Connection
(downloadable for other OSs) You will notice the install
adds Terminal Services Manager, when you are connected
through terminal services you can remote control a user
so he can see you update a user account or what ever you
need it for. There are also technet docs on setting up
the TSAC (Terminal Services Advanced Client) which you
can put on a web server and it will allow you to connect
over the web (IE only).
good luck,
jake