[M.Sudoku]

Xfce is just as customisable as KDE or GNOME. For proving this, two detailed posts appeared on Xubuntu's blog. Where in the first post Linux has been shown being converted to Windows Vista with full transparency, glowing buttons and Flip 3D.
In the second post by pushing the limits of Xfce's customizability even firther, Linux has been converted to Mac OS X Leopard even with dock and cool animation.

Make Xubuntu look like Windows Vista
Make Xubuntu look like Mac OS X 10.5 “Leopard”

[Silare Alvreon]

May I ask if Xubuntu supports Compiz Fusion with it though? Because that would allow for a Spaces-esque functionality and some Cover Flow window switching.

[M.Sudoku]

Yes, click here.

[Johnnyboy]

Nice customization, but I still love the look and feel of Ubuntu.

[M.Sudoku]

Here's how to make your own theme with Xfce 4.4