They may all be evil, but Zarqawi unlike Saddam or Osama actually has nads.
Zarqawi endlessly moves from house to house planning attacks. While Saddam hid under the ground. And, while Bin Laden hides in a cave in the middle of nowhere away from the battle.
I could never see Saddam jump out of a fast moving car (and under a bridge to avoid the UAVs) like Zarqawi did in Febuary.