I am helping my friend to manage a small network at his company. One of two servers they have is a Server 2003 providing terminal services. Another is a Server 2008 SBS running the domain controller, Exchange etc. My part includes helping setting up new user accounts, and configure their terminal server environments. There are things users could do themselves if they were more knowledgeable, but with this process being done only once there is no reason to spend hours on training just for that - how to point a third party app to the right database, how to move the Documents folder to a mapped network drive etc. So I just do it all for them. And that's where the issue comes in - from time to time I have the need to login as them to configure things properly. The company is just several people and the standard practice so far has been - they tell me their password, and I do the rest.
I know this is a very insecure practice and I would like to change this. I am not very experienced with Windows servers and do not know how I, a network administrator, can login as another user. Linux servers have the su command that allows admins to login as other users. Is there anything like this in Windows? Am I looking at it from the wrong side?