Telnet

notsure, telnet is a communication program in windows, you cant contact other computers with it etc. go to start>run> and type telnet, and it will start, find out yourself

It's kinda similar to the remote desktop that can be found in XP.
It's a somewhat more archaic version, that using a text-based command line interface, to allow you to access other systems, etc.

It's a simple program for running a remote shell. You can connect to other computers if you have the ip address etc

i tried entering my friends IP. it doesnt work though...

The computer you are trying to connect to must be running a Telnet server (able to accept connections). Be aware that Telnet is not secure. All commands, passwords, etc. are passed as clear text (unencrypted) and are subject to interception by someone else.

it is very useful if you are trying to connect to a UNIX machine from your windows machine. you get a command line only interface.

unless you are planning on doing this, you can probably forget about this

As said before, Telnet is another Internet protocol that allows you to connect to a server. The Internet used to be mostly Telnet, before the http protocol came along.
Today, it is mostly used by system admins who need access to the server from remote (for example when they get a page that the server crashed in the middle of the night).  Telnet is indeed not encrypted, that's why there is SSH. SecureCRT is a good SSH encrypted Telnet client.

telnet is an indispensible program for us system admins. As was said, if you have the ip address or more commonly the host name you can log into any of your servers anytime (unless they are really crashed) from anywhere with an internet connection.