This is really a matter of opinion, as you can have just one speaker in a room, or set up a whole system. Generally, if you are looking for the best quality sound, you will want at least one center and one left and right speaker. However, some higher-quality speakers, such as the Klipsch R-5502-W described above, will serve the purpose of multiple speakers. For the ultimate home theater experience, it is recommended that you have at least five speakers, and an amplifier capable of handling that many.