i have a canon 50d. i have about $600 to spend. i was wondering if i should for for the 580 exII or a slightly used to new 70-200 L glass?

We have no info on your kit nor knwo what you are using it for.

I'd get a cheap flash of some sort and a used 70-200/4 non-IS.

EBH

aahhh it a 50d with the kit lens of 28-135. im looking for a good all around lens. from what ive read the 70-200 is one of the better lenses for the money