Do you need subwoofer for music (no movies)

Hi,

I do have Yamaha RX-620RDS a/v receiver and a pair of Quadral (german
company) front and rear speakers. I use it mainly for music (60% of
time), movies from divx (30% of time) and DVD movies (10%) of time.

Is it worth to buy a subwoofer to enhance that system? Will it help in
normal music listning? I heard subs use to be too slow for music and
they do not help really?

Any oppinions?

Marcin