To change the browser that fires up when you click on links in various GNOME applications, just change the default browser in the GNOME control center (you can bring up the panel in question directly by running gnome-default-applications-properties). Enter something like opera "%s" or mozilla "%s" in the Custom Web Browser box.
GNOME 1.4 has a capplet for changing window manager. In GNOME 2.x, you can change it
If the above fails because you have a previously saved session with metacity, then loading the Gnome Session manager, deleting 'Default' and then adding a new 'Default' seems to allow sawfish to start.
According to Twisted Radix, this doesn't work on GNOME 2.12+.
Using the default gnome-terminal(1) settings when double clicking on a filename containing a + character, only the portion of the filename up to the + is selected. This can get incredibly annoying!
Fortunately there is a very simple fix, right click on your terminal, choose 'Edit Current Profile', Add + to the end of the "Select-by-word-characters' text box, Close.
To revert to the default panel configuration:
gnome-session-remove gnome-panel gconftool-2 --recursive-unset /apps/panel gnome-panel &