This war was about establishing a sphere of influence in the middle east.
Have you ever stopped to think why we now have troops in Iraq, Afghanistan, Saudi Arabia, Bahrain, Turkey, and Kuwait? It is about exerting influence. The terrorists are pissed because we are on their 'holy soil' and the Wahhabi public aren't too pleased about it either. On top of that, we have Iran building nukes, Palestinians attacking Israel, and Syria screwing around too.
Our major military focus USED to be Europe. That's not the case any longer and the new theater of conflict will be the middle east. We now have Iran surrounded with troops on either side, as well as a way to move our troops to Iraq (easing the Saudi politcal scene), and a way to strike at terrorist targets anywhere in the middle east. (Ironically, where most radical Muslim extremists originate)
Yes, part of this influence does concern oil. However, you have liberals and Democrats (notice, they're not always the same) driving around in their SUVs (John Kerry is an example) bitching about the price of oil, yet, also refusing to drill in the US reserves (Alaska) or exert political/military influence in the middle east to control it.