XWin32

It has a 30-day full-feature eval period, after which it's still full-featured, but you can only run it for a few hours at a time, IIRC. I'm using it right now and the only problem I have with it is that I can't figure out how to start it without it asking me if I want to conncet via XDMCP or rshell. A cancel-click every once in a while isn't a big problem, though.