With the recent advancements to the Task Manager, incorporating Resource Monitor, you can easily see the bandwidth usage from Terminal Services.
In short, it all depends on the settings you have used and what you're doing in the remote session. More actions require more repaints. Below are two shots I've taken while in an RDP session to a Windows 2008 R2 server.
The first screenshot, only Resource Monitor open (~3.6KBps):
![enter image description here](../../I/static/images/8984a18b56b270fc49638c72bf1c1cf5924a778a60c76903c6fa0525dfd17348.jpg)
The second, a YouTube video streaming (~951KBps):
![enter image description here](../../I/static/images/47d7f780b97fb3c923d044adce0c5d92298c04a7870eae2947e63d5a6fd6a5f0.jpg)
Hourly bandwidth consumption at rates like these can vary from ~12M to 3.4G+. Unless you are watching video over RDP, the higher end of the ladder is highly unlikely. For normal activity at 1024x768 resolution with standard settings I'd estimate about ~25M per hour.
3I suggest you get a bandwidth monitoring program, and measure it. – derobert – 2009-09-19T17:24:52.060