I think one of the factors that gets missed in discussions of the Iraq War is the extent to which improved medical care is masking the full extent of U.S. casualties. This article from CNN points out that the survival rate of soldiers arriving at field hospitals is twice the rate in Vietnam. They do not give enough data to figure out what that means for overall casualty rates, but it is certain that death rates in Iraq are much lower than they would be with the medical care that was state of the art during Vietnam.
I've read previous articles that described some of the advances that have been made. While trauma care has improved, the major advances are in reducing the time before a wounded soldier reaches a medical facility and, even more importantly, advanced medic training for our troops. Apparently, every soldier and marine now gets almost as much first aid training as a combat medic received in Vietnam. Combat medic training has similarly advanced since Vietnam. At every step of the way, starting with their buddy giving them first aid all the way up to advanced trauma care at a combat surgical hospital, our guys are getting better medical care than ever. And that's great.
But we need to remember that saving more wounded solders' lives makes the war look less intense, without making the war actually be less intense.