Wintin.Net is a free windows client for text-based muds. It looks after the basic communication with your mud as you would expect, but also includes a range of features to make your mudding experience easier and more enjoyable. It's the ultimate tool for a sophisticated player, but simple enough for a novice. Features include everything from MXP, MCCP, addin capability, windowing, to multiple scripting languages.
http://www.wintin.org/