I have a 4.1 speaker set and a 2.0 speaker set on the same system (6.1?, lol) It's not really true surround I don't think. I just got 4 speakers on the table, and two on the wall above the monitors, sub on the floor (actually on a box that is on the floor). It just adds extra power to the setup. I got a random sound card that has a place to plug in 2 speaker sets at the same time. Don't got a clue what it is, but it works so I don't care.
Didn't vote because mine's kinda weird...