[eugovector]

Yes, if it's a functioning fireplace, it's not a great idea.

I'd close the whole room up, and put surrounds on stands. It's will be better to sit closer to your TV anyway; assuming 42" 720p, you'll want to be ~63" away. When company comes over, you can kick the furniture out to wherever it's comfortable for entertaining, and move the surround on stands.

What about the wire for the surrounds?

I hear you, don't want to trip over those. If you own the place, I'd pop a hole for them under the couch and run them under the floor or carpet. If you don't own the place, square everything up like the second picture and wall mount the surrounds.

Actually, looking at it now, that second option makes more sense in both scenarios.