anyone use this stuff under their carpet? http://www.coolandquiet.com/product_detail.cfm?Prod=1 it sounds like it works quite well, but it sounds a bit thick. is 3/4" too thick to put underneath my carpet?

Haven't used that particular stuff, but most insulator compresses quite a bit once it has the weight of the carpet and seats on it. You might have to trim it away from the sill plates some though.