They have a Windows 2000 server and Windows 2000 Pro machines, so would I need to buy any licenses?
It's certainly one thing you can use Terminal Services for and a way to make supporting those remote users much easier. You can indeed use RDP over a VPN -- that's a popular way to provide secure access to remote users. You will not need to buy additional TSCALs, but you will need to set up a license server. Please see the licensing white paper at http://www.termservhub.com/other_resources/definitive_qa.php for details.
This was first published in February 2004