The last few days I have been using KDE 4 with Kubuntu and I am quite impressed
with its responsiveness. It is much more configurable than when it first came
out and it seems stable. The default settings are too large for my taste, so you
may have to change the taskbar, icons and font size to make them smaller. If you
are a KDE 3 user, then you might want to see what the fuss is about. It probably
won't interest hardcore Gnome users much, although the first thing that I do in
KDE is to move the taskbar to the top and KDE 4 allows that, too. This allows me
to run Avant Window Navigator at the bottom with the Gnome menu on it.

It should be available for Windows soon or at least that is their goal. So
wouldn't that be nice for dual booters to have the same interface no matter
which OS they are in. At the very least it will give Windows users a taste of
what the open source community enjoys already, a choice of desktops. If even a
small proportion of those decided to give Linux a try afterwards, it could bring
in lots of new people because the user base for Windows is so huge to begin
with. Or the opposite could happen and dual booters could spend more time in
Windows. Time will tell, of course, but it could be an interesting turn of
events when it comes to pass.