Undoubtedly the war in Iraq killed many civilians and this is a tragedy. Even one single death is terrible, but it has to be recognized that there inevitably must be trade-offs, and alternative results should be considered. This is not a moral choice - it is intrinsically part of the reality we live in. Deciding to do nothing to avoid casualties, means that one has decided (consciously or not) that the potential results of inaction are less dire than intervention - in other words there is a trade-off.
Anyway, as Mark Twain said "There are three kinds of lies: lies, damned lies and statistics." It is amazing that everyone bandies around the figure of 100,000 civilian victims, from a debunked Lancet study, while the UN itself, that neocon bastion, estimates that the number is a quarter of that (via Instapundit). It is nonetheless a terrible number, but honesty and good-faith would give the war critics some credibility (which I find they often lack).