Forget the specs of each body, you need to work out which system works for you.
I've heard a lot of people say it's like testing out a wand in Ollivander's wand shop in Harry Potter - one generally 'fits', and I can't disagree from my recent experience when buying my first DSLR.
Go into Jessops, play with Canons and Nikons, and you should find that you favour one over the other. Specs are irrelevant - both companies make excellent cameras and you'll change bodies more frequently than lenses (good lenses can last decades). Once you buy into a system, you'll probably stick with it for life if you intend to build up a lens collection, so that's what you need to focus on.
As an aside, if you think you'll only buy a body and a kit lens and leave it at that, it's worth exploring mirrorless cameras. There are many competing systems (micro 4/3s is one of the more well known ones) and we don't really know yet how long the mounts are going to be around for (Nikon's DSLR 'F mount', on the other hand, has been around since '59 IIRC), but the size and weight benefits are enormous.
