What makes a WindTunnel a WindTunnel? As many of you know, I just bought one last Friday, and so far I like it. I also have a NIB Tempo, and was told that was a low end WindTunnel. Is that true? What's the difference between the two? Sorry for the silly questions, but I never was really into Hoover (except for the Convertible we had when I was younger, and the Concept One my friends had), and am just getting my feet wet with this brand.