Congrats Charles! You're going to love this camera.
Dont get rid of your XTi, because you'll probably want te crop factor when shooting wildlife or need the extra range, but this is like jumping from a Ford Escort to a Ford Mustang Cobra! No comparrison!
The larger frame of the 5D, the scaled back dials, larger screen, better processor, full frame.....I could go on and on.
I absolutely love Full Frame for scenics and wide angles, and as long as I'm not trying to reach out too far, I love the images it gives me.
Probably the only thing I dont like about it is we tend to shoot alot of sports of action type photography, and the 5D is SLOW. But it's not made at all for that type of photography, so it's my own stupid fault for not having a 1D Mark III or a Mark IIn for when the need arises
Good luck, and have fun with the camera, I know you'll love it