traditionally, hi-fi speakers would be a pair in 4ohms or 8ohms impedance; that was about all that one set had in common with another.
cinema systems come in 2.1, 5.1 and now 7.1 – the .1 denotes the subwoofer; the remaining 2, 5 or 7 speakers will probably also be 4ohms or 8ohms, and again, that’s about all they’ll have in common.
basically, try before you buy. If you can take a laptop loaded with iTunes & your favourite songs to the shop, that will help you get a balanced opinion. And yours is the only opinion that counts. Good luck 🙂
of course, I’m no specialist, not even a serious hobbyist, so no doubt someone will be along soon to shoot me down in flames, but hey, what the heck