Xfce4, LXDE are two good environments to try, I think. If you don't want to try Openbox now, try Fluxbox, it's easy to get going with.
When I had my netbook I did run Gnome 2 and it ran pretty good. Gnome 3 may be heavy for it. On my current tower system, I'm running Xfce4 and Gnome3 & KDE4.
Like it is...Yusef Lateef