Canon and Nikon are definitely the best for beginners, I'll tell you that, so you got the right companies.
But, I was in the same shoes as you 3 months ago, looking for my first dSLR.
What did I end up choosing? The Nikon D40. Depending where you are, you may only be able to get the D40x.
Regardless...here's why
-It's cheap. Really, you can't get a dSLR for 499 dollars, except this one.
-It gives you most of the things you want in a dSLR, at a fraction of the cost. Really, something like the D80 won't give you that much more than the D40.
-It's still as stylish as the Nikon D90 or the Canon Mark II (?).
-It's smaller. You're used to the point and shoots, which are smaller, this is a good inbetweener, I guess. Not as big as the other cams, but bigger than pns's, so yeah. And it's easier to carry around.
-It is very helpful, with the small things. I know what f stops, shutter speeds, and the mechanics of it all are and how they happen to work now, but not starting out. There is a little graphic in the lcd where it will show you how the lens is, like the aperture and shutter speed. It really gives you a visual.
-It's easy for beginners, but still gives you that professional edge when you get better.
The only thing I'd recomend is look at other lenses. Of course start with the kit lens, but it, like pretty much any kit, is lowER quality, so definitely look into primes, telephotos, fish eyes, wide angles, macros, etc.
Hope that i had helped you, and if you have any questions I'll try to answer them
!