I think most of the info you need is on the NT Reghack site. Tip 175 gives a general solution that I believe works for both Win95 & NT clients and it uses a kixtart based solution.175 » Prevent users from logging on more than once. http://www.jsiinc.com/TIP0100/rh0175.htm
For further info see Tip 120 which is an introduction to writing a kixtart logon script.
120 » Solve those logon script problems. http://www.jsiinc.com/TIP0100/rh0120.htm
Here is an alternative solution that uses a freeware utility. I believe that this solution is NT specific. You would have to shellout to execute this script. This might be an alternative to the NT solution that is offered above.
0296 » A better way to prevent a user from logging on more than once. http://www.jsiinc.com/TIP0200/rh0296.htm
This a freeware utility to help with logging off any user who trys to logon twice.
184 » Logout is Freeware and works on WinNT and W95. http://www.jsiinc.com/TIP0100/rh0184.htm
