I don't know what manner of hideous ways Vista finds to waste your resources, but there's no reason why a good OS shouldn't show such system resources as being in use when it has little to do - they'd be being used to cache data temporarily. Indeed it would be wasteful to do otherwise. Obviously when you have a more pressing need for the memory those caches would be discarded. But like I say, I've no idea what Vista is doing. Don't particularly want to know either