I've heard where the Oreck one is good. http://vacuum-cleaners-online.com/or...r-purifier.php
It's got a permanent filter which is cleanable and reusable. It also moves the air throughout the room more so than other brands, therefore trapping more dust and contaminants. I saw the advertisement for it on t.v. If i were to get one, this would be the one i would get. Try it out and tell me how you like it. I think it's got one of those deals where you can send it back if not satisfied, but not sure. I remember the t.v deal had that, but not sure about this place posted above.