Putty is a telnet/SSH client for Win32 Operating systems (Windows 95+). The best part about putty is that it does not require any installation, nor any other system packages, you can just download and run the exe. Putty also can handle various terminal types built in, and can store connection profiles into the registry.
Information from the homepage
PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms, along with an xterm terminal emulator. It is written and maintained primarily by Simon Tatham. The latest version is beta 0.60. LEGAL WARNING: Use of PuTTY, PSCP, PSFTP and Plink is illegal in countries where encryption is outlawed. I believe it is legal to use PuTTY, PSCP, PSFTP and Plink in England and Wales and in many other countries, but I am not a lawyer and so if in doubt you should seek legal advice before downloading it. You may find this site useful (it's a survey of cryptography laws in many countries) but I can't vouch for its correctness. Use of the Telnet-only binary (PuTTYtel) is un-restricted by any cryptography laws. Latest news: 2007-04-29 PuTTY 0.60 is released