I think the reason a lot of people are uncomfortable with the decision to go into Iraq is because:
a. we hadn't finished what we'd started in Afghanistan and that is still proving to be costly not only in dollars but our troops' lives
b. we were given the reason of weapons of mass distruction then "oops sorry" it's because Saddam and the Osama are in cahoots..."oops sorry...I'll come in again." Right, he's a genocidal dictator who needs to be taken out. When you're lied to repeatedly about the rational behind it, you sort of throw your hands up after awhile.
c. while there have been successes in Iraq, this has gone on far too long, cost far too many lives, and still there isn't a real resolve to it yet...meanwhile Afghanistan goes on and now there is the possibility of conflict with Iran because let's face it...no matter where you stand pro or con on the war, it wasn't as well thought out as it should have been.
That said, and I know you and I are on opposite spectrums politically, I think going after Milosevic was the right move and I would actually like to see us have the resources to do much much more in Darfur...because frankly, their situation is far more dire than the Iraq we invaded in 03. However, I think right now we just don't have said resources because of the missteps we've made regarding Iraq.