Megapixels aren't the be all, end all, in the DSLR world. One thing you should look into is the availability and price of additional lenses. Kit lenses, for the most part, suck. Nikon's are notorious for having rediculously expensive lenses in comparison to Canon. Just sayin...
If you're still stuck up on Nikon...get a D40 and be done with it. Its plenty of camera for 80% of the people that use them.