Vista Tutorial - old winterm 3000 series cannot connect to Vista Ultimate RDP remote desktop connection

I have an old Winterm 3000 series (from around the year 2000). I can connect
to a Windows 2003 server using an RDP connection. However, when I try to
connect to Vista Untimate using RDP remote desktop I get an error message:
Client and Server versions do not match. I assume this is referring to the
version of the RDP protocol ( I believe Windows 2003 uses RDP protocol 5.2
and Vista uses RDP protocol version 6, but don't quote me on this).

My question is: Is there a way to dumb down the RDP protocol version of
Vista so that my Winterm will talk to Vista? I have no problem connecting to
my Vista Ulitmate using the Microsoft RDP client (mstsc.exe).

Thanks.
Dan.