Find a theme on freshmeat that looks like gnome to you (or make your own, sorry, no tutorials), then apply it. I think IceWM has a desktop setter, but I don't remember what it is called. You can always use Feh to do that (just add it to your .xinitrc with the command line option to use the desktop).
HTH
EDIT: Just saw your screenshots, and FVWM2 might work for you as well (I have seen FVWM screenshots very similar to yours). I've never really used FVWM, so I can't help with it, however.