I think you are on the right track with your speaker choices. The VP150 is an excellent center with good off-axis dispersion. I wouldn't use the QS4 or 8s as front L/R speakers,however. They aren't designed for that and would probably "wash out" your front imaging -- especially when you're listening to stereo material.
That being said, M22s would be your best choice for non-tower front speakers, but if you wanted to save some money -- and especially since you're getting a great sub -- you can easily go with M2s instead of M3s. The M2s and M22s have a flatter response, and are therefore more accurate. Not everyone likes an accurate speaker, though, since they can sound bright and somewhat harsh in certain environments.
The main reason to go with M3s over M2s or M22s is if you like a bit more warmth in your sound, or if your room can be characterized at "bright" or "lively" (i.e. lots of hard, reflective surfaces).
The ideal setup, in your sutuation would be M22, VP150, and QS8s. You could easily step down to M2, VP150, and QS4 without a significant sacrifice in sound quality.
