OK to address the audio in Vista first...
Well I have Ultimate 64 and i gather it doesnt support 5.1 via digital.
Youd need to use analouge multichannel if your after 5.1 in ultimate.
Not sure if your after this yet you mentioned an amp and tv.
I didnt think this was the case Mr Latte. I havent looked into it in much detail but wont AC3Filter help? I may be wrong.