[Geoff F]

In reality, there isn't that much difference between a 350D and a 40D in terms of image quality. Although, admitedly, I wouldn't want to switch from my 40D to a 350D but that is mostly due to the feel and balance of the 40D particularly when used on a bigger lens.

I never use a fast burst rate, personally I think it tends to increase camera shake problems. There are a number of other easier to use functions on the 40D but you can get along without these for now. Just don't hold a 40/50D in your hand so you won't get tempted.

So get a better lens now, but keep saving for the future.