Don't commit to any brand without investigating all your options. I don't know how you settled on the Nikon D40 but be sure to check out the Canon Rebels, Pentax K100 (or upcoming K200), etc. You want to make sure the camera feels right in your hands, and that the interface suits you and your wife.
Lens wise, Nikon and Canon have the most complete lineup of modern lenses, prices vary though and often Nikon tends to be a bit pricier for some things but at the lower and consumer end I don't think the differences are all that big. Pentax makes clever design decisions with regard to interface and features that other cameras don't quite match, but to day their modern lens catalog is more limited (they have decades of lenses compatible with their DSLRs though).
If you ever get in to it and want to find other lenses to use on the D40, it will not AF with lenses that lack AF-S; their silent, high speed in lens focusing motors. So that rules out a lot of older (and some current) lenses that might be more affordable. The reason for this is nikon left the focusing drive motor out of the D40 body which some lenses require.
Also I don't know anything about cameraaddict, but that price is low, too low. If it's too good to be true it usually is. Check them out on resellerratings or ask on a photo forum and you might get more feedback on them. If I've never heard of it though, I'd be very hesistant to buy from it IMO. The best and safest places to shop are places like Amazon.com, Bhphoto.com, adorama.com, keh.com, calumet, keh and there are some others I can't think of off the top of my head.
Personally, I wouldn't worry too much about image stabilization in lenses. It's nice but not needed, and a faster lens would usually pay off more than a slow lens with some kind of stabilization. Nikon and Canon in particular are putting stabilization in a lot of their lenses now though, so it's easier to get affordably.