We recommend using RealVNC 4.1.2 for Windows, that version can be configured to run on Vista but requires a particular setup as described here:
So in order to make VNC server on Windows Vista works properly, the workaround resolution (at least until the VNC developers to come out with proper fix or update to address the new security constraint in Windows Vista) is to run VNC server in user mode.
[list]*Ensure that you have the exceptions to allow incoming connections to winvnc4.exe or to port 5900 (or any other port number that you want to allocate to VNC server listening port), or simply turn off firewall.
*VNC server is detected as potentially unwanted behaviour in integrated Windows Defender. Create a rule to ignore this warning.
*If you want to newly or fresh install VNC server, do not install the VNC Service by not checking or selecting the ?Register VNC Server Service? option, or else you will have ?Not Accepting Connections? error even when trying to run the VNC Server in User Mode.
*If you have already install VNC Service (register VNC Server as a service to start automatically when Windows Vista starts), unregister the VNC Service.
*If you want to configure settings of VNC Server, right click on ?Configure VNC Server? menu item and select ?Run as? for administrative privileges so that the VNC configuration tool can access to the relevant parts of the registry.
*Then start VNC Server in User Mode (may need to Run as Administrator too), and you will be able to connect, remote control and access to Windows Vista computer desktop from another computer properly.
This information was originally posted here with some additional information: http://www.mydigitallife.info/2006/12/13/workaround-to-run-vnc-server-in-windows-vista/