The options menu only has "notify but do not update," with no way to turn them off completely. But, since Firefox is apparently just as pushy and stupid as Microsoft programs, Firefox absolutely refuses to stop accept my answer of "no" and then never ask me again... I can't imagine why anyone would willfully update to Firefox 3.6.4, since this adds 1.5x memory to Firefox which is already a HUGE memory hog according to task manager, by adding another process which does absolutely nothing useful at all (any "crashed" pages have to be reloaded anyway - and that's all of them, not just one). It should be pretty obvious to Firefox engineers that no one would want to ever downgrade from 3.6.3 to 3.6.4 , so I can't imagine why it keeps asking me to update, but I definitely need to know how to turn it off.