Original from HERE
Copy of orginal post:
I mentioned before that Windows XP does not allow concurrent sessions for its Remote Desktop feature. What this means is that if a user is logged on at the local console, a remote user has to kick him off (and ironically, this can be done even without his permission) before starting work on the box. This is irritating and removes much of the productivity that Remote Desktop brings to Windows. Read on to learn how to remove that limitation in Windows XP SP2