[ADK_Jim]

Rather than a lens you might want to consider a set of extension tubes. Focusing on closer objects requires that you move the lens further from the film/sensor plane. Macro lenses simulate that with movable internal elements that bend the light rays to focus on closer objects. An extension tube however, physically moves the lens out. It is simply a hollow tube with the necessary electronic connections to make your camera controls work. If you have a sharp prime lens it would be cheaper to get a set of tubes than to invest in more glass. The one potential problem is if you are using the stock EF-S lens that comes on the XTi, it won't fit on the EOS extension tubes. The tubes fit the body and you can put any of the EOS EF (film camera) lenses on them but not the EF-S digital only lenses with the back focus feature. There are non-automatic tubes (no electronic connections for AF and f/stop control) advertised on eBay but I have yet to see any automatic tubes made for the EF-S lenses. If you have an EF lens that you can manually control the f/stops on you probably want to control the focus manually anyway on macro shots.