On gnome I didn't have a problem hiding the top bar only the unity 2D.
The compiz customizing add-on failed to appear when installed. guess it
is only for Unity 3d. Maybe I need to look harder for a different ubuntu
release made for netbooks like releases before 10.04 I think that unity
would work great for new users but I have to say without an answer to
this I will not install on anything new.