Kmeleon - Windows Gecko Browser
Have it working on windows NT 4.0 workstation over here.
Kmeleon is surprisingly good for a one man show although he seems to be emulating somewhat older versions of IE (3.0?).
What it does best is just show the potential, though. I'd swap over to an IE clone that was running gecko instead of IE in a second. And for Windows, I want something Windows specific that uses all standard evil (tm) stuff that Windows is actually good at, so I don't have to suffer more than I already do using Big Bill's "operating system".