Force the uninstall, as you are going to re-install it right???
A forced uninstall (--force --erase), would just erase the sawfish stuff.
Or you could just do a (--replace-files --force --install) on the sawfish RPM too.
The only other thing you may want to do also is to create a new user(using linuxconf of course), and copy that users GNOME startup files from thier $HOME to your $HOME. I have seen ( and continue to see) GNOME barf on HORKED© $HOME stuff. I currently have a machine with a HORKED© user and am just being lazy by not fixing it.
Later!