Hitler killed at least 10 million people with his genocide, but you could blame many of the 75 million WW2 deaths on him. Stalin killed at least 20 million, possibly closer to 45 million.
As a result of Bush's actions, at least 75,000 died in Iraq and it's 650,000 as of July 2006 if you think the statistical study done by Johns Hopkins is accurate. I haven't read their study so I can't comment on their methodology but I am sure that the 75,000 number is underreporting the deaths in Iraq.
Probably the number is somewhere in between. Let's go with 300,000 and let's say Hitler/Stalin level evil is 30,000,000 deaths. That's two orders of magnitude. It would be closer to three if you distributed the blame for the war across the entire Project for the New American Century.