What were the political possibilities of doing that at the time, given all the hoops he had to jump through to attack Iraq? It is easy to be an internet Rambo but quite another to get it done.
A few forays into Syria, in hot pursuit of terrorists and those Syrian regulars aiding them, would have shown our resolve. A few bombings of Syrian installations that support the regime would have further cemented the notion. Following that action, reaching out to elements within Syria that are not allied with Iran could have followed. Syria's regime's support is very shallow, and the ruling Allawis could be toppled with a minimal amount of US support.
Iran should have been a major focus of our efforts from 2003. Read Michael Ledeen and all his pleading for the Bush government to take action in Iran, from 9-11 to the present. He is not an internet Rambo, nor am I. I believed then that the Iranian mullahs can be brought down, but it would take an active policy to foment revolution and support those who would do the toppling. We should not go into Iran except to prevent them from having nukes under a mullah regime, and then only to destroy the programs that they have. We can defeat the Iranians if we wish, but at a much higher cost than Iraq, and at the cost of weakening our global reach in places such as east Asia. China is the biggest winner so far in this war on terror.
Don't be a Bush apologist all your life. He's done some good things, but not lately.