I'd like to know how important it is to have 'matched' surround speakers. My plans are to buy just the front 3 speakers from the Monitor Audio range to ensure that they're balanced and use my old hi-fi speakers for the back 2. (Tannoy Mercury M3)
I don't want to throw out perfectly good speakers if they'll be fine for the occasional rear effects!
(Denon AVR-2105; Denon DVD-1930)