you chosen two entry level DSLRs from the two top brands, if your not careful this will turn out into another full blown debate about which brand is better. Have confidence in knowing that whichever one you go for, you'll think you've made the right decision. Just make sure you think into the future as you'll probably stick with the brand you go with forever really because you'll have all the lenses and equipment specific to that brand.
For my part I think that Canon maybe has more lenses avalible at lower prices and a few years ago they were a clear leader between the two brands, however now Nikon has turned it around with their latest cameras. I went for Nikon and love it because I can potientially use any lens they've made in the last 50 years on that my D60, so some of the classic lenses that cost pennies compared to modern equivilants can give you professional quality. However im sure there are benefits with going for canon, i just have no idea about that side really