I picked up a Sigma 17-70 2.8-4.5 Macro lens to replace the cheap 18-55 Kit lens for my Canon 350D and am quite impressed. The price is also right for a lens of this standard (tip : Photocontinental in Brisbane are selling the Canon mount for $430).
Here is my quick evaluation including star test:
http://www.pbase.com/terrylovejoy/sigma1770
There is also a detailed review at:
http://www.photozone.de/8Reviews/len...2845/index.htm
Terry