Hi, I'm fairly new here. I've posted 2 photos and read your posts daily to try to learn as much as possible. I have a Rebel xti with the kit lens, the nifty 50 f/1.8, and a Sigma 70-300 f/4-5.6 APO DG Macro. I'm going to be giving my son the kit lens for the xti he's getting for Christmas, so I will have a gap in my small collection. I was considering the Canon EF 17-40 f/4L USM Ultra Wide Angle Zoom Lens. I want to start getting some good glass and this seems to be within my budget (well, at the top). I can pick up a used one for about $80 less than new. Any reason not to buy used from a reputable dealer? And would this be a good choice to round out my slowly growing collection? My next choice after this would be the Canon EF 100mm f/2.8 Macro USM Lens because I think macro shooting would be fun. The Sigma really isn't a true Macro, but it's a good start to whet my appetite. Any suggestions/recommendations would be appreciated.