missing xfce xubuntu desktop at boot

[Ryan Moszynski]

i installed xubuntu, but have since downloaded the kubuntu and gnome
desktops to try them out on my machine.  I am back to using xfce.  the
problem is that now every time i log in, in order to be able to see my
desktop, i have to click a checkbox at:

menu/settings/desktop settings/
Allow Xfce to manage the desktop


How do i set this option from default so i don't have to each time I
start my machine?

thanks,

ryan