I'm just dying to get my hands on this game to "relive" my youth with my two boys, 9 & 6. Unfortunately my house is mostly carpeted ....
Don't let the carpeting stop you. The only weapon it will affect is the crossbow, which shoots its ammunition disk across the floor. You could either play without the crossbows (there are three other weapons per side, not to mention the expansion sets), or--if I was you--try using a book as a firing base for the crossbow. If you angle the shot upwards a little, you should be able to "lob" the disk far enough to hit your target. Or try using two of the elastic bands on it (recommended by Jim "panzer attack" Patching in his review). That might give you enough thrust to shoot on a carpeted surface.
Come to think of it, those crossbows could be used for a nice friendly game of Power Crokinole as well ....