For 7.1 you'd have 4 surround speakers. Surround Left, Surround Rear Left, Surround Rear Right, Surround Right. The other three are normal L, R, Center.
I can't imagine 7.1 is all that much better sounding than 5.1 but I haven't actually heard 7.1 so I don't know.
As yet,there`s no such thing as 7.1 You may have seven speakers,but the two rear centers are mono. The future of 7.1 is to add a height channel ( yes,above your head )