The 40D is newer. Both good cameras but I'm a Nikon guy so don't know specifics.
When you start shopping on line be sure to see our dealer feedback forum to avoid the rip off places.
Just about all Dslr will have all the settings you'll want plus more. They all have multi shot(frames per second) capability though some have more than others. I think they all have black and white capability but most photographers convert to black and white in post editing. It comes out better. Time lapse is available on some and not others. I think xti has it but not sure. Anything below D200 won't have it for Nikon but D200 and up do.
The statement that concerns me is that you want to spend up to 2,000 and have everything you need. That will never happen. You'll have everything you need until you want to do low light and find out you need a faster lens and/or tripod. Then you find out on camera flash doesn't really cut it and you need to buy a flash. And of course memeory cards, cleaning kits, long lens, short lens, filters, diffusers, editing program,etc.
There's no way to tell how much you'll need and believe me they will continue to come up with stuff. I think I spent about 1800 on my original purchase and have spent at least that since and I don't have the high quality "pro" lenses as it's a hobby for me. Lenses are where most of your expense will come if you need the high quality necessary to be professional.
I'm getting from your post that this might be a surprise gift. I advise against that as what a photographer prefers is really a personal choice.
What experience does your wife have?
What type of photography does she want to do?
Do you have a camera now? What brand? Is it a dslr with lenses?
Have you looked into Canon, Nikon, Sony, Pentax, Olympus? All make good cameras and have their own followings.
Don't mean to overwhelm you but just want you to get an idea of what you're getting into.
And I really, really, want you to bring it up with your wife and find out what she wants/needs.
Best of luck and don't give up but keep coming back and ask questions. Read the reviews section on dif cameras, ask more questions and learn the vocabulary.