Guest TIA,
There have been two "Studies" carried out by John Hopkins. The results of which were published on 29th October 2004 (Comes in handy for 2004 Presidential Election) and second with an estimated mid-point figure of 650,000 on 11th October, 2006 (Comes in handy for 2006 mid-term Elections).

Two quotes relating to the 2004 "Study":

"The study makes the controversial conclusion that: "Violent deaths were widespread, reported in 15 of 33 clusters, and were mainly attributed to coalition forces." and "Violence accounted for most of the excess deaths and air strikes from coalition forces accounted for most violent deaths."

While Newsday reported:

"The most common causes of death before the invasion of Iraq were heart attacks, strokes and other chronic diseases. However, after the invasion, violence was recorded as the primary cause of death and was mainly attributed to coalition forces—with about 95 percent of those deaths caused by bombs or fire from helicopter gunships".

Iraq Body Count puts the figure much lower and provides least and worst cases. Figures given for the former have been confirmed and verified by two sources, figures for the latter have only one source.

I would tend to go on what has been verified, as opposed to what has been projected.