Canon 10D and 20D
when you buy a digital SLR you're really buying into a lens system moreso than the bodies. Manufacturers will upgrade bodies almost every 12-18 months (well canon does, nikon has issues), so you might wind up upgrading the body more often than your lens collection.
canon vs. nikon is an older battle than pc vs. mac, go to
www.dpreview.com and check them both out, then go to your local camera store and get some hands on time (bring your own cf card and take some pics with both) and see which one you like better.
canon or nikon, you'll be happy. Me? I'm partial to canon because i like their lenses better ( i think they have a broader range of selection and better quality) but that's just my opinion, canon fits better with what i shoot.
if you have any Canon questions let me know.