The 'net' is full of Nikon vs Canon Forums.
I shoot Canon, but only because I was given a bunch of lenses!
There's also Sony and Pentax to consider.
At the moment, I believe Nikon has the edge in low-light photography.
Canon the edge in outright resolution and capture speed.
This could change at any moment.
One seaon's miracle DSLR is next season's kludge.
Consider the DSLR as part of a system, rather than an end in itself. What sort of photography you THINK you will want to do, and which components offered by which companies fit the bill. Remote activation? In camera processing abilities? Flashes? Lenses? The list is long.
In my experience Canon long lenses (135mm+) are 'better' than Nikon's.
Nikon's wide-angle, better than Canon's
I prefer Nikon ergonomics.
I prefer Canon's IS sytem to Nikon's VR (same/same really but Canon seem to implement it better).
Nikon has awesome flash control, Canon remarkable high-speed AF.
You see where this is going.....?
Nowhere...fast!
Only two absolutely factual points:
Nikon cameras will take any Nikon lens built in the last 50 years. You won't have all functionality, but it means you can get a seriously beautiful manual lens and have it work on your DSLR.
Canon out-sell Nikon by a significant margin. Getting 'extras' for your Canon like lenses, flashes, accessory cords, gizmos of most sorts, is generally cheaper and there are more nearly-new bodies on the market at knock-down prices.
Try fossicking around on forums like:
www.dpreview.com and
www.fredmiranda.com.
You'll get no end of opinionated nonsense, but also some wisdom and objective reviews.
Good Luck!
Send me any money you
don't spend.