The prospect would have seriously divided NATO and hurt US relations with Russia and China. I wouldn't be surprised if by 2010, NATO either has collapsed or exists only on paper.
As for the invasion itself, the US would have toppled the regime within weeks thanks merely to its overwhelming conventional armaments.
The occupation would have been a disaster. I'm not sure whether a Baath Resistance would form, but rival sectarian militias would quickly fill the void. Iran and Syria would have backed Shia militias while Saudi Arabia would back Sunni ones, causing a proxy war in the heart of the Middle East. Eventually there would have been Yugoslav-like violence with a similar outcome.
In OTL, Bush left office in disgrace with the subprime mortgages crisis. ITL, he would have been reviled to the point Republicans are afraid to mention him.