I am having a similar problem in Vista with my speakers. My front set will not work ( though Windows says they are fine ) and the rear speakers work just fine, thank you. If I switch the cables, the former front speakers ( now rear speakers ) will work and the former rear speakers will not work ! Anyone have any suggestions why the front speakers will not work in Vista ?
Just for the heck of it, have you tried plugging your Polk speaker cable into the rear speaker receptacle ? That way you may check to be sure your speakers do work...
If anyone can clarify Vista sound problems many of us would be grateful.