You *did* get some good answers there, not sure if I can add much. Your room size is fine for either M22s or M60s, although with the M60s you'll probably want to "use more of the room" than you would need with M22s.
To that end, I might suggest you move the seating position a couple of feet closer to the back wall, move the TV and front speakers further into the room as well, and position the surrounds just BEHIND the second window rather than between the windows.
If you are thinking of building bookshelves on the front wall you would probably have to do this anyways. If it were my room my first thought would be to leave walking space between TV and bookshelves, rather than putting the TV on the shelves.
Something like this :
http://good-times.webshots.com/photo/2873960110048161985HqMfIoFor some reason I can't upload to my normal web hosting area so you're gonna have to click on the link.
Moving the seating position away from the midpoint of the room will also give you more options for subwoofer placement.
