Command-line connection to listening client from Vista machine?

[Philip Herlihy]

On XP machines I've set up a script which invokes a connection to a
listening client:
 
>vinvnc4.ext - connect  MyClientHost.MyDomain.com
 
- very useful.  This doesn't work on Vista.  Can anyone advise on how I'd do
the equivalent from a command-line or command-file?  The Vista box has VNC
running as a service.
 
Phil, London