Terminal Services disconnection

We have just moved our remote users from a WinNT with Terminal Services using Citrix to a Win2K server with terminal services. While it is still too early to tell, some of my users are still experiencing disconnection from the server. All users (various O/S) connect via DSL. We currently have 10 users connecting on a server with 1GB of ram. Generally, they will be idle for a few minutes (to take a phone call or some other interruption) only to return and find themselves disconnected. Are there adjustments on either the PC or server end that could improve the situation? Thankyou in advance.