The place I'm at runs IE 6.0. I think it's due to user inertia and resistance that it doesn't get switched over to Firefox. What I'd like to see is a version of Firefox that emulates the visual appearance and workings of the IE 6.0 interface (down to the title bar, icons, etc.), but under the hood and all the rendering is really being done by the latest FF. Updates would just go in automatically with no user intervention.

Seems simple enough, and there are some themes/skins for FF that purport to do this, but they don't go far enough, or aren't polished. They end up looking a little crufty (for instance, they don't get rid of the structure of the forward/back buttons in the latest FF).

If somebody came out with a seamless "sheep in wolf's clothing" solution for IE 6.0 -> FF, it would be a lot easier to get users to adopt it. Does that help wider FF adoption? No, but I think that's a separate issue from pure user "acceptance."