The Canon EOS 400D (Digital Rebel XTi)is a clear improvement over the 350D (Digital Rebel XT). The sensor has been upgraded to 10.1MP, though users shouldn't really see a dramatic difference in image sharpness. The buffer size has been increased, the LCD size is larger, there are more AF points, an RGB histogram mode has been added as have picture styles. There is now an ultrasonic sensor cleaning mode to remove dust from the sensor. I think the update from the 350D to the 400D is more significant and worthwhile for users than the 20D to 30D update was.