I'm a huge Nikon fan. In fact, I've moderated at
Nikonians :: The Nikon User Community for over 5 years.
Despite being a Nikon fan, I harbor no illusions about the Nikon vs Canon debate. They both make superb gear for all levels. They are both currently engaged in a one-upmanship free for all. If the latest Nikon looks like the best camera in the world, give it a few weeks and Canon will top it. A few weeks later there will be a bigger-better-faster-more body from Nikon. Evaluate the gear on a unit by unit basis. Hold them. Use them. Research them and then buy what you like. You can't go wrong with either brand.
There are differences in the companies though. In _general_ Canon is more innovative, they release new products at a much faster rate than Nikon, they often push the 'stat' game in terms of marketing and design and they are less inclined to maintain compatability across their line.
Nikon in the other hand is slower to release products, is probably less responsive to consumers desire for bigger, better and faster. They tend to place an emphasis on ergonomics. They stick with backwards compatability to an almost bizarre extent. I can (and do) use a 35 year old Nikon lense on my year old D200.
I will not even get into the full frame vs DX sensor size debate. For most people with less than $3000 to spend on a body it is moot anyway.
So you pick what you want. Again, you can't go wrong with either brand.
But, if you want to go Nikon, the D80 is among the best bangs for the buck in the Nikon DSLR line and the 18-70 kit lens is an exception to the kit lense=junk rule. It is not a fast lens but it is optically excellent and very affordable, particularly used from places like
www.KEH.com.
As for shutter lag, this is much more a problem in point and shoot digital cameras and even then does not really have that much to do with motion blur in your images. Motion blur comes from slow shutter speeds, either the camera moving or the subject moving. Shutter lag is discussed in regard to DSLRs but it is usually a trivial issue.
Again, don't fret too much over brand, even Sony and Sigma make good digital SLRs. But if you do settle on Nikon, come see me over at
Nikonians :: The Nikon User Community .