I prefer Orstio's bridge SMF 1.1 RC3 / Joomla Bridge 1.1.6 you can have separate databases & installing/uninstalling is really simple.
Thanks for the information but I am stuck. I install Joomla and SMF through the Fantastico installer and can't figure out how to have Joomla and SMF use the same database.
I think that you need to do a manual install of SMF and when you get to the part where you enter in the database details you put in the name of your Joomla database ad your mysql username & password.