AF: 20D vs 40D

Hi all,

Is it a good thing to upgrade from the 20D to a 40D
Still find the 20D a very good cam, but when i did take some concert pics, it was not very good focusing at all times... i have oof pics whein i was shooting there.
Is the 40D better in low light focusing?

Greetings!

I've upgraded about a month now. I've used mine with my trusty Sigma 70-200 f2.8 in low light football matches and it appears to focus very quickly, but I've had quite a few OOF pics with moving players which is concerning me.
When it is sharp, the pics have very little noise even at 3200 iso which I find is an improvement over the 20D.
My 20D was pretty effective at long distances with the full 200, but the 40D struggles and seems to focus only when the subject gets relatively close. I'm thinking of getting it checked out by a Canon service centre just to be sure.