In order to get that Blu Ray player to work on your PC, be prepared to drop some coin on a pretty decent graphics card, most of which won't pass the audio at all. Processing capabilities are a different issue entirely. On the audio side, I suppose you could get a card to send the PCM stream out to your receiver to decode, but that's pure speculation. I bet that there is an audio card that can either do that, or decode the Blu Ray signal internally and pass it via multi-channel outs.
For my money, I think you're better off with the turn key stand alone player or a PS3. All that hardware (not to mention software compatibility issues and no tech support) to buy makes me concerned - and I looked into this option a couple of months back before deciding to go the stand alone player route.
Also consider that, if you buy a stand alone player today - get one cheap, try eBay - you can always hustle that one to a second TV when the players get cheaper and better.
Just seems like a bigger headache than its worth.
