You obviously need a receiver (just the receiver without the speakers since you already have those). If the speakers are good, I suggest you get an ONKYO (they are very very good and somewhat affordable)
There are few TV's on the market that will drive external speakers, and even fewer that will drive external surround sound speakers. Unless you have one of these very few TV's, you will need an amplifier for your speaker system (incorrectly, but commonly referred to as a receiver if it has integrated AM/FM tuners).