I own a Canon SLR 20D for a couple of years already and I absolutely love the camera. Now that Canon has a 30d in the market which came out Feb. 2006. Upgrading from 20d to 30d is definitely out of the question as I do not see a need for the upgrade 1.8″ to 2.5″ LCD vieiwer. To me, it’s just not worth it if you already possess a Canon 20d.
If it’s your first dSLR and if you are thinking of owning a 20d or a 30d, then you may need to consider the price different that you will be paying versus the difference in performance and specs that you will be getting. You are looking at a price difference of about $300. Speed and performance wise I do not think there is a major difference between the 20d and the 30d. With the 30d, you are getting a larger LCD viewer, 2.5″ versus 1.8″ on 20d. It does have a 100,000 shutter cycle warranty – when I read this, does that mean that my 20d will die within my 100,000 pictures taken?
Anyway, the ultimate decision is up to you, but I love my 20d and I do not see a need for me or anyone to purchase a 30d.