By default, Vista installs without telnet available. I know, I know, you should be using SSH for everything now, but sometimes you just need good old telnet. Here is how to enable telnet in Vista:

1. Open ‘Control Panel’

2. Select ‘Programs and Features’

3. In the left column, select ‘Turn Windows features on or off’ (get ready for the annoying UAC prompt)

4. Check the box next to telnet (and any other obscure services you may want enabled), and wait while Vista thinks for a while.

Thats it, now you can administer your network devices in as unsecure manner as possible!
-Ben (@ ArsGeek tips)