I have a K850i as well and have been fiddling around with things like this too, until now I haven't come across anything like using your phone as a PC speaker, but if I do I'll PM you.
Try these forums though, they will be very likely to be able to help you (I would have tried there but I'm capped): Http://www.esato.com . If you find out how to do this, please share...
I suspect that his phone will be connected to his computer via bluetooth or wi-fi (don't know the phone's capabilites), and he wants to stream the sound playing on his computer through the phone so that he can use the phone as a mobile speaker or something similar.
Thanks for the heads up! I will check out esato. And the reason i wanna do this is i left my speaker set up at my student digs as its a large thing to lug around, now i just want something to output sound to so i can show some funny videos to the family- its not the same with earphones. And second cause i think it'll be a really cool idea. Im suprised noone has made something that can do it.