well, if you keep the zoom you've already got, I'd get a 70-200mm first, in which case you've got a greater range with which to play with. On a 1.6 crop, 200mm is a decent amount of reach. a 24-105, while excellent, won't really give you much more than you've already got, from a shooting flexibility standpoint. The quality might be better than your current zoom, but I'd prefer to have more options first...