In our Cisco NetAcad classes we had utilized built in Windows telnet client (of course we have putty instead), which was available in each system till Windows XP by default. In windows 7 the telnet client is not available by default, but we simply may do it available in few simple following steps:
1) Open Control Panel and choose Programs and Features
2) From the left meny choose "Turn windows features on or off"
3) and in the "Windows Features" window scroll down and check in Telnet clients
4) just wait few seconds let the Windows to activate this feature
5) after that the telnet client is available from the Command line tool