Unit is purchased from UK. Not form US Acer. Does it make difference.
i have installed the drivers from UK support web page.
Better to deal with Uk then, as USA may not have what you need. Also of note, is that sometimes installing driver without uninstalling existing driver doesn't work, for some reason.
You might want to consider, once you find it, downloading Dolby Home Theatre application for VISTA, uninstall what you have, then install what you downloaded.