I'm too tired for a pro canon reply. xP
Go to any camera store, try out all the entry level cameras, go home, read reviews (dpreview.com) and then buy the one you liked the most. And a tip is not to get the most expensive one but to rather spend money on a lens, because that's what matters the most. When you become better at photography you can consider getting a better camera, but with you being a beginner it would be a waste of money.
Mp and image quality isn't the same thing. My friend shoots with a Nikon D50 (6 mp) and his images have the same quality as mine. You can even get really good prints with a 5-6 mp camera. I mean big prints. But oh well, the Canon 400D will go down in price when Canon release their new 450D (in april) so you'll be able to get it cheap.