Go somewhere where you can physically hold both:
I have had excellent Canon, and also excellent Nikon cameras, and am well disposed to both - when I made the switch to a DSLR, I tried both - in the end the better fit in my hands of the Nikon was the final decider - I have large hands, and the slightly smaller body of the Canon simply felt a little clumsy - You want to be concentrating on the shot, with your fingers instinctively over the relevant controls, which I couldnt do with the Canon - but it may suit you more. Camera quality wise, the minor differences in functionality are so minor that they are largely irrelevant - however, a year or so after buying the entry level Nikon DSLR (the D50 at the time) I moved to the D200 - and wow what an awesome machine, incredibly solid, fabulous results, I really wish I had taken the plunge right at the start.. about 13000 images later on the D200 I am still over the moon with it, (and am still learning! getting better all the time though!) and I think that is key - its important you are relaxed with your hardware and simply enjoy your kit..
Top tips, whatever you buy:
Having made your choice of model, buy a couple of photography mags and scout for the very best price in print (Wilkinsons are often good). THEN take the mag into your local Jessops, who will always price match it, so you always get the best deal, BUT - you also then get Jessops 30 day no question return, refund or exchange - so if you change your mind, you dont lose a penny! Also - they do the best insurance - about 10% of the price, covers for 3 years, any failure, AND any damage even accidental, with new replacement, only theft isnt covered - money well spent and peace of mind - I let my teenagers use my full kit and all the lenses without worrying - they're careful for sure, but I dont fret about it!
means you get the kit you want, the best price, somewhere local to take it to if you have issues rather than some website, 30 days to play and make sure its what you want with no risk, and ongoing peace of mind (remember the insurance is a proportion of the discounted rather than full price too!)
No I dont work for Jessops - I just love this stuff and have spent lots of time researching best way to get it!
You wont be disappointed with either model -
www.dpreview.com has some really excellent reviews and forums for support
hope that helps..