Thinking of upgrading my Canon 400D to either a 40D or 5D but not sure what to do. Should I go and get the 40D now or the 5D or wait for the upgrade to the 5D.
Firstly, don't get that camera now! Wait until the end of the month when the second Canon Cashback scheme of 2007 is expected to start. These aren't UK prices but as an indication of what to expect check out this post
5D prices are relatively low and may get lower even without that cashback offer. As I see it your biggest issue is that your EF-S 17-85mm IS USM and EF-S 10-22mm USM won't be compatible. If you want to keep the full frame equivalent fields of view then, ignoring any cashback offers and money from selling the EF-S lenses, I reckon you are going to have to budget between £700 and £1100 on glass. All of a sudden that 40D might be looking to be excellent value. I guess it depends how badly you need the IQ of a 5D.