From everything that I've read here, I would say the OP would probably be best off with a 550D. This coming from a 40D user! 
But I would suggest trying a 40D first. Perhaps you could buy one and try it for a few weeks - if you don't get on with it then you probably won't lose much selling it on again

But I would suggest trying a 40D first. Perhaps you could buy one and try it for a few weeks - if you don't get on with it then you probably won't lose much selling it on again
