You may or may not know this already, but when you install Vista, by default, the telnet client is not enabled. I happen to still use it quite a lot so it was a bit of a surprise to me when I tried to use it for the first time. Enabling telnet is rather easy, here are the steps.
Open control panel
Select programs
Select turn windows features on or off
Select Telnet Client
Click OK
You now have a working telnet client.