I install Ailurus which gives you many extras for Ubuntu and one of the
things that it can do is change the buttons with one mouse click. It is
useful for many other things such as setting up servers, adding repositories
such as Medibuntu, finding the fastest mirror and lots more. It is like
Ubuntu Tweak, but better in some ways. I have both installed. Just because I
can.

http://code.google.com/p/ailurus/