I don't think that's the case, both OS has all the newest updates, using the newest livewire 3.0 from SB, both using directX 8.0, and it's really really noticable..
I think I had this problem once of my speakers sounding really low... but it was just a win98 problem then.. I had my digital output turned on when I didn't have a digital output card... but I checked and it's nto on now.. is there another place or something where I can check to see if it's turned on?