hi,
the free edition has this info in the documentation
http://www.realvnc.com/products/free/4.1/winvnc.htmlIf Fast User Switching or Remote Desktop are used, then VNC Server will connect session zero to the console in order to allow it to be accessed. Other sessions cannot be accessed by VNC Server Free Edition 4.1
From the features it shows that free version does not work on windows2008/vista
http://www.realvnc.com/products/download.htmlas when i checked by installing the vnc free version on windows 2008 it does let me set to NT authentication. So you can try personal edition trial and see
bhanu