I recently got a $100 gift card from Dell. I want to buy a new lens for my camera (xsi w/kit lens). Dell has this EF 75-300 mm f/4 - 5.6 III Telephoto Zoom Lens for $160. In my previous post I explained that I mainly do portraits of people, and I admitted that I do not know much about lenses or the technical aspects of photography. I'm learning though. In your opinion, should I buy this lens? Would it be any better than the kit lens I already have? I really don't want to spend the extra $60 if it's not going to be any better quality. I don't think the new lens has IS, as my kit lens does. Please help! My gift card expires soon!