I'd try using true throat mic's, not the cheapo xbox 360 throat microphones. True throat microphones are transducers that pick up the vibration from your vocal chords and produce sound. Cheap throat mics are simply standard microphones that are mounted on a strap near your throat...which doesn't help background noise at all. I don't have experience using one of these for xbox live, but i've used a different one for motorcycles and karting. they work quite well if you can find a decent one.
For xbox, I use a Tritton Warhead 7.1 headset, which allows for totally wireless communication (not even a chat cable to the controller), but would really negate the use of your surround sound. I use a Fanatec CSR Elite (while a great wheel, has a completely useless communication port), so the Warhead 7.1 is really my only headset option for racing with it. I'm more than happy with my headset, but its a $300 unit, so not for everyone. Before the warhead 7.1 came out, i was using the Tritton Detonator headset, which is wired, but has a physical button for muting, and the sound quality is quite nice, for only $70.
Formula Forza Founder