Those Dyson's look nice, Rainbows and Kirby's are absolute crap. If you want a real vac though that will literally last you a lifetime (warrentied for 2 lifetimes) check out silverking I used to sell these and own one myself.
http://www.silverkingvacuumcleaners.com/
They are expensive as hell though but really cant be beat in the long run (difference between price and cost)