What are the dimensions of your room?
I have found you really need a very large room for 7.1 to be worth it over 5.1. If you sit in the sweet spot 5.1 sound 99% like 7.1. The nice thing about 7.1 is covering more seats and off axis seats. It might be worth dropping down to 5.1 if it allows for better speaker placement (all speakers equal distance from the main seat) and or better speakers. P
Also what is your movie/music mix? High-fi speakers are a waist for home theater and there are specialty speakers that are better choices (extreme output, built ins etc). If some music is mix in it is worth getting nicer stuff.
Anyway look at the center speakers as it will make or break your surround system. Choose a brand that has a large good center.
