I'll echo Mark's response - if you plan to use it for anything other than macro shooting, get the Canon EF 100mm f/2.8L IS Macro USM lens. I have one, and it's amazing. But, macro requires a tripod, even with the IS, unless you're shooting in full daylight and still willing to sacrifice some DOF. If you intend macro only, get the Canon 100mm non-IS. If you'll use it for other shots, get the Canon 100mm IS.