Matt, without knowing your room size and layout I can just give a little input on my own system. I had a budget similar to yours and went with the following: M22 fronts, QS4 surrounds and a single M2 center. I seriously considered going with M3's upfront, but ultimately am very happy with the M22. No upgradeitis at all. The QS4's are great speakers SACDs and DVD-s sound incredible. You can always try the QS4's and upgrade to the QS8's if you feel it's necessary. I went with a single M2 center as a cost saving option and it works well for me. I would like to compare the sound of the VP100 or VP150 to see if it would help with dialogue for those on the room's periphery. If you will be able to sit in your "sweet-spot" the M2 is a viable center option.
What do you have for a receiver? I'm running HK's cheapest HT receiver the AVR 130 and for an entry level unit it does a good job. Good luck.

M22's, VP150, QS4's, HK 630, HSU VTF3-MKII