Easy answer found here:
http://ubuntuforums.org/showthread.php?t=181034
Copied and pasted here, in case the thread gets lost:
To change the Window decorations i.e the placement of the minimize,
maximize and the close button on a window in gnome please do the
following:
Step1: Alt+ F2 (this will bring a run dialog window)
Step2: Enter: gconf-editor (and hit the RUN button)
Step 3: You will now get a Configuration Editor Window . Please follow
the following directory path: apps>metacity>general>button_layout (in
the options window) and change the layout/sequence as you please.
(Read the directions at bottom of screen)