Save your money on the Litter Maid. I had one a couple of years ago, and it ended up in the trash can because of the cat waste getting caught in the rake.
The rake has to be cleaned by hand every couple of days with a knife or simular to keep it operating properly. If you want a real automatic cat box.....go with the Litter-Robot. I just got mine recently and "love" it. I will be posting a review on the Litter-Robot in a few weeks at the forums. The Litter-Robot is nearly twice the price of the Litter Maid Mega, and it appears to be worth it. Just go to their website and read the raving testamonials from people that own one
You get what you pay for with this unit. It is built like a tank. The company has excellent customer support and they offer a 45 day full money back gaurantee minus shipping if you or your cats don't like the Litter-Robot for any reason. My three cats all used the unit within 3 hours of my installation.
I will report more in a few weeks www.litter-robot.com
Also, the litter Robot just won "best cat product" at www.beststuff.com
on 6/26/03. Good luck with what you decide.