telnet is no longer installed by default in Vista.
To install telnet, follow the instructions in the Help and Support center. Click Start Orb -> Help and Support -> type "Telnet: frequently asked questions" -> click on first result -> click on "How do I install Telnet".
Instructions are reproduced below:
===== How do I install Telnet?
By default, Telnet is not installed with Windows, but you can install it by following the steps below. To install Telnet Client
- <LI class=step>Click the Start button , click Control Panel, click Programs, and then click Turn Windows features on or off. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
<LI class=step>In the Windows Features dialog box, select the Telnet Client check box.
- Click OK. The installation might take several minutes.