If its just for speech and background music then a small system of a maby 500 watts will do ya. A pair of cabs with 12 inch drivers and a small desk....
If you want to address a large crowd and pound their heads in with bass you may want a stack / separate subs and tops.
the second one obviously ! I have two massive speakers and a box with loads of dials and levels..its been used to death for 6 years ! I need something more user friendly and portable !