While comparing the features of Canon 400D and 1000D, I've noticed that Canon 1000D has an improved DIGIC III processor, over the DIGIC II for Canon 400D.
From Wikipedia:
The DIGIC III Image Processor was advertised to deliver superior image quality, faster operation and extended battery life compared to its predecessor.
Will a newer version of the DIGIC processor provide visible improvements of image quality? What about when shooting in RAW?
I understand that newer versions may perform faster (when focusing, or a higher frame rate) and have features such as face detection and live view, but that is of no importance to me.