i posted on 5dot1 a question,same question here:

anybody know of a converter from optical or coax(from dvd) to 5.1 analog?

can't cost more than new dvd with component out and 5.1 out.if my friend has to buy a new dvd to have 5.1,we both win,i'll buy his (used) because mine only has optical and s-vid(which i have no problem with)but i'll get to upgrade to component(cheap)