canon 40d and nikon D90, which is better?

In my opinion,I think D90 will be better than canon 40d because it is the main camera in middle level of the nikon amount .And the live view mode is a little bit better than 40d .And the live view mode can help you taking photo from a lower point .Also canon cannot control any AF ,BUT NIKON can be set to AF-E ,Af-S
it is very useful

Canon CAN control AF mode: One shot, AiAF, Ai Servo

I believe D90 is a better bet, 40D is simply historical, and myself, had some very unhappy photographic experience with Canon DSLRs.