I just tested Ventrillo v3.0.3.Alpha.8 x64 and tried to connect to some testserver and it worked.
It can’t be a server feature/role you need to install first before you can connect to a Ventrilo server so try to find out what is blocking Ventrilo from connecting to the server. Try disabling all security software installed and also Windows Firewall which can be turned off in Start -> Run -> Services.msc.
Good luck!
