http://news.bbc.co.uk/1/hi/world/middle_east/6135526.stm
With 100 bodies being being brought into hospitals and mortuaries every day, I would suggest that the estimate of civilain casualties in Iraq of 100K is a low one. This figure cannot include those directly killed in bombing raids during and after the invasion (easily 20-30 thousand) and other instances where whole, or even identifiable, bodies couldn't be found. There is also the thousands of people (including entire families) who basically would have been killed in cold blood in their own homes, not naming sides but obviously including Fallujah and as a result of sectarian rivalry, who's bodies where probably just left in situ or recieved a quick burial under Islamic custom to consider.

As a, probably still concervative, estimate of civilian casualties, it must easily be over 150K. Probably 170-180 when certain specific, deliberate murders are taken into consideration. This still leaves accidental casualties (i.e. heart attack victims, road accidents) who would normally be saved if hospitals in certain areas weren't already bombed or overloading with war victims. Many hosptials ran out of or were short of vital medicines due to the war and sanctions, leaving the most vunerable to face a death sentence.