I already have a 4.1 audio chip integrated in my motherboard and I'm
currently using a pair of stereo speakers.
I'm quite interested in upgrading to surround sound, specially for dvd
movie playback.
I would like to know if I need to buy a completely new set of 4.1
speakers, or if a pair of 2.1 speakers (for front audio), plus my
current stereo speakers (for rear sound), will do.

NOTE1: the audio chip is CMedia's CMI8738 (I know it's not perfect,
but it's already integrated on my motherboard, and I´m on a limited
budget as you may have noticed).

NOTE2: my motherboard has separate output for front and rear channels.

thanks in advance.