Depends where I am...
On my main PC, I'm in a simple 2.0 speaker configuration, one either side of the monitor... or basic stereo headphones.
On my laptop, usually just the stereo headphones.
In front of the X360 & PS2, when the laptop is wired up to the external Soundblaster, I get 5.1 surround (which, honestly, is just upmixed from stereo as I don't have any optical connectors) and that's patterned with 2 either side of the widescreen monitor (TV replacement), one center directly underneath the monitor, subwoofer to the left of the centre speaker (and therefore also under the monitor) and back left/right spread out high a good three metres back and out from the front speakers; they're more "left-right" than "back"...
You can tell where I choose to listen to music, can't you?