I'm pretty happy with my P&S, too (it's a Panasonic Lumix DMC-TZ1), but it's been pooping out on me lately for action shots.
If you all have Canon Lenses, I would seriously check to see if they are compatible and I'd probably stick with Canon for you guys. I've seen some AWESOME shots taken with Canon DSLRs before, but I know there are a lot of die-hard Nikon fans here. I went with Nikon because I don't have a DSLR yet. I've never had one, this is my first. AND my in-laws have the Nikon D40x, so most likely their 55-200mm lens will work on my camera (I hope) and I can use it when they are around, if I want.
I am definitely FAR from an expert on cameras, I just know that usually Nikon fans are Nikon fans and hard pressed to try anything else, and the same goes for Canon fans.
I don't know anything about the user-friendliness of Canons, either.