Thanks for all the feedback - it looks like a 5D Mark II is still some time off, given the current prices of 40D's!
Problem is, even when the 5D Mk III comes out and the Mk II gets cheaper, so will the 40D most likely.
Glad to know the 24-105mm will still work, but would have to get rid of the 17-70. I want to get a wide angle (10-22) anyway so I guess that might be a chance to
