Maximum PC

I have a a problem, upstairs via hdmi im watching my TV, downstairs via DVI I m watching my Projector. Everytime I need to change sound i just right click on the speaker icon and either set as default hdmi for upstair or speaker for downstairs (projector audio is through audio out to a speaker). My question is this, If i extend the screens and I can watch both tv and projector, how can i hear two different audios at the same time for the individual screens ? One person watching a movie upstairs and another watching the projector downstairs.

By the way Im using an ATI 5870, and I will be replacing the speaker downstairs with a receiver feeding my suroundsound, I will most likely connect that through the fiberoptic from receiver to pc.

Is there a solution to this? perhaps buying a sound card like asus xonar? another ati card? crossfire? anything???

You *SHOULD* be able to do this with two sound cards.
I have a suspicion that you could set each video program on a different audio out. I managed to do this once, but I have absolutely no idea how I did it last time.
I will try to find out once I receive my new sound card.

The way the DirectShow API works it will only output sound to one device. It's absurd, but Microsoft would say it's working as designed. With Windows 7 your ability to change this behavior is non-existent. Unless someone has written a sound API for Windows that I haven't yet tried.