sudo apt-get install xubuntu-desktop
Then log in to XFCE. Voila. Or kubuntu-desktop, for a widget-rich KDE env. Or lubuntu-desktop for a very very resource light desktop (though XFCE in Xubuntu is nearly as light). Or install E17, or ... or ... or ...
Ubuntu has made some good moves at the kernel and library level ... and has pretty good repositories. You can take advantage of both those facts, whilst using the desktop you prefer.
Are there alternate desktops for Windows 8, anyone?
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