I have the setup (but without BL2) that Pedro suggested and I can only recommand it, it's sound is great, especially the BL7.1 does an excellent job with movies.
If you go for the BL7.4 solution, you should get a BL2, as the center speaker does not go very low (compared with 7.1) and because the BL3 are somehow weak at low frequencies, especially at high volumes.
Music washes away from the soul the dust of everyday life. - Berthold Auerbach