Telnet is a useful application for troubleshooting various connectivity problems. Unfortunately, Windows Vista does not have it installed by default.

However, it is very easy to install telnet on Windows Vista by following these simple steps:

1. Launch Control Panel, select 'Classic View' and double-click on 'Programs and Features';

2. Click on 'Turn Windows features on or off';

3. Locate the Telnet client from the list and check its box;

After following the above steps you will be able to use telnet with Windows Vista.