Personally I would consider a second hand body... at the moment you can pick up a nice EOS1D Mark 2 for abour £600, although I did cough out on a mark 3!
However if used is out the question go for the 40D it is a fantastic camera and I would strongly recommend one. Just think if they are going to release a new body which inevitably they will you could get a brand new 40D at a heavily discounted price and still have a great camera.
Ive got a couple of EF-S lenses so cant go for a 1D (I love my 10-22mm too much
Im heading to New York for 2-3 weeks for Christmas and New Years, whichll probably be shortly before a 50D is due out, so I should be able to pick up 40D body for $700. Ive already spotted it for $850.
Hopefully well see a new 17-135 from Canon this year...