Re: My $650k house is now going to be an $850k home
I wouldn't go Maggies for the sides and rears, for the wall mounted MMG's are a bit of a hassle and won't look as good as your ML's. They are good for the money but I would use ML's inwalls for the rears and sides.
Meridian is good. McIntosh is very solid and lends a bit of richness to the ML's but I would seriously look into Bel Canto. You could Mono block every channel for the price of one McIntosh amp by going Bel Canto. If your space is large (sounds like it will be) I would feed the ML's 1000 watts per channel. The Meridian/Bel Canto matchup is AWESOME!!!!
Don't forget Krell. They have a grip of new processors coming early '08.
You may have to double up on the center channel for a screen that size...