I got myself kind of a fancy computer at the beginning of this year, and I've been enjoying a couple of games on it, using Windows. Since I've got a nice motherboard, it's coming with a couple of audio outputs, 3 of them for a 5.1 configuration.
But since I prefer to wear headphones instead of using speakers, I wanted to have all my sound going through a single jack. Unfortunately, configuring anything on Window is challenging at best, because instead of well commented configuration files and manpages, you have to click your way through oblivion.
Anyway, here is what you need to clickityclik on to get it done:
Control Panel → Sound → Playback → select your output → Configure → Audio
channels: Stereo → Apply.
That's it, you can now enjoy proper sound, without the middle channel missing.