Kit lenses tend to be built down to a price, so that the kit comes in at the right price.
I don't rate kit lenses highly enough for it to be a buying decision.
When I bought my 20D the Canon and Nikon kit lenses were about equally awful.
Now that both kits include IS lenses, I don't think there is much between them.

To me the most important thing is how the camera feels, and how it works.
You're buying into a system, not just a body and kit lens. As soon as you invest money later on in better lenses, you're hooked.

For me, the position of the main control wheel on top of the Canon right by the shutter release was so much more usable than the Nikon placement on the front of the camera that I bought the Canon despite the Nikon feeling more comfortable in my hand.
The grip fit my small hand well, but I didn't feel as good using it.
So having spent nearly an hour in Jessops, I left and bought the 20D body only from a Canon professional retailer a couple of hours drive from home