I've got great new 5.1 sound system and tons of MP3 and I don't want to use my front speakers only. Making the computer treat the rear speakers like the front ones and playing the same sound on them is an idea, but I was wondering whether there's a way to convert the stereo sound to 5.1 in real time. Of course, I realize that it will only be an imitation and not real 5.1, still it's better than nothing. Any ideas (that don't involve buying expensive sound cards)?