which lens.....?

hi...ive recently bought a 300 D and am on the lookout for another lens for it, which one of these 2 lenses is the better investment.
thanx for your time.

EF55-200mm F4.5/5.6 MK2 USM or EF 75-300mm f4/5.6 USM MK3

Image quality wise there is not a lot in it, the 55-200mm probably has the edge.

Have you considered the 100-300mm F4-5.6 USM - this lens is better optically than both those and is also constructed much better. It has internal focus and AF in generally better.

I would rather go for the 70-300mm f4.5-5.6 DO IS USM. It is a very nice 'standard' lens for the MkII as well as the 20D and very, very sharp indeed if the operator knows what he is doing.