I would definitely ask THEM to provide the source stating that there were 100,000 deaths. They should have cited the source when posting the article (although libs never do). Since they didn't, I would challenge them and ask them to provide proof or a source.
In my rebuttal letter I'm planning on using just a few words to cast doubt on the 100,000 figure while pointing out that our losses could be much less if we decided to unleash our full military force from the air. Like the Israelis, we take more casualties because we fight humanely with respect to civilians. I also want to say "If the war is about our controlling Iraq's oil, where's my 50 cents per gallon gas?"
Thanks again for the input!