Phil,
with those M60's and QS8's you have one heck of a start for a home theatre!
I'd get a VP150 and an EP350 to complement them. If you choose to go without Axiom for the sub, you might want to take a look at the new SVS that is a cube, not a cylinder. It has a much nicer appearance!
The VP150 is a stunning center. Voices sound so pure and are pushed out in such a soft manner that you'll never get ear fatigue. Some people prefer an M2i. You could always order both and compare. I prefered the VP150 to an M22ti. The M22's, however, are superb as main speakers. They are the best bookshelf speaker, and the M60's are widely considered the best tower. They have been reputed to sound very much alike, with the M60's have, obviously, greater bass output.
