If you're going to buy consumer lenses, I don't know why you just don't go for the Tamron 18-270 f/3.5-6.3 VC, which is more practical.
But then, why are you getting a 40D-class camera?
But I wouldn't get any Canon Rebel or Nikon D40/D40x/D60.
You can get cheaper cameras with built-in stabilization from other vendors and
make one of the lenses an f/2.8 if you go third-party.