Flash player 7 is here:
Note, that it may just work with Flash Player 9, if you install it manually exactly as follows, first close firefox and remove all traces of previous install, then:
1. Get the '.tar.gz' from here
2. Extract it, and open up a terminal at that location, 'ls' should say:
Readme.txt flashplayer-installer flashplayer.xpt libflashplayer.so
3. Run the following commands:
rm -f Readme.txt flashplayer-installer
chmod a+rwx,go-w *
cp flashplayer.xpt ~/.mozilla/components
cp libflashplayer.so ~/.mozilla/plugins
4. Start firefox and go to some flash sites and see if it crashes.
EDIT: Also note that this is a local install, I guess you could also install it system-wide to '/usr/lib/mozilla' or '/usr/lib/firefox' instead of '~/.mozilla' (you may have to 'mkdir /usr/lib/mozilla/components').