Well, bin Laden in interviews prior to 9/11/01 said the reason he was fighting the US had to do with (a) the Israel-Palestine issue, (b) the US dominance of Saudi leadership, and (c) the deaths of 200,000 Iraqi children under UN sanctions promoted by the US.
Now, as far as (a) is concerned, the US is all for an even-handed solution to the Israel-Palestine issue. So bin Laden really didn't have an issue here against the US.
As far as (b), bin Laden is as much a product of the US-backed Saudi regime as anybody can be. So this is rather pretentious as well.
That leaves (c), that the US was starving to death 200,000 Iraqi children a year through sanctions. That was the only heavy-hitter that bin Laden could use as a propaganda argument in order to justify the slaughter of 3000 Americans on 9/11/01.
This is how the Dictator Game works. Saddam starves the Iraqi people, and blames their plight on the US, and the Arab world holds up Saddam as a hero.
And this is how the Freedom Game works. The US removes Saddam, and suddenly the Iraqi people aren't starving anymore, and the US is hailed as the liberator, and the Islamic radicals are left looking like a bunch of jerk-asses unable to accept their own moral failings.
By invading Iraq and bringing an end to the suffering of the Iraqi people, Bush has removed the one 'grand' excuse (read: pretense) that the Islamic radicals had in engaging in mass terrorism against the US. It's one thing to compare 200,000 dead Iraqi children to 3000 dead Americans and argue the gruesome mathematics of retribution. It's another thing when it turns out your own side was also responsible for those 200,000 dead Iraqi children.
The liberation of Iraq essentially means that Islamic terrorism is a spent moral and intellectual force that can no longer hide behind a facade of lies. Sure, there are the True Believers who'll linger around for a few more years -- but what of the next generation? How do you raise a new generation of True Believers, when the younger generation can easily see with their own eyes that it was the Islamic radicals themselves who were the abettors of oppression in Iraq?