Hi - I've had a quick scan thru posts, but nothing specific to my query - so dumb-ass question alert

I've got the 70-210AF beer can (+ others) and use it with a 9000 and 700si. If I were to pick up a 7D or simiar, what's going to be the outcome? What basics are/aren't going to work? What does the digital sensor size do to the effective "length" of the lens? (ie will a 70-210 become more a 35-135 or a 80-300?)

Cheers all. M