I have had a Canon 40D for a while and it’s a GREAT camera. Before that I had a 20D which was a big step up for Canon, but the tiny LCD and more limited auto focus made the trip to the 40D a great upgrade.
But this 7D, wow – better/faster auto focus, better LCD, better view finder, 18 megapixels, much better high ISO capability (lower noise), better controls, high def video, on and on and on !!!!!