regular.joe, you should read this book:
Imperial Hubris: Why the West is Losing the War on Terror
It does a very good job at explaining why Al Qaeda and other terrorist are attacking America.
"I sincerely wish that we lived in a world where we could go about our lives on a daily basis, and not be concerned with someone trying to undermine or destroy that way of life. Sadly, that is not the way things are."
This is a very good quote and the people that are waging a war on America feel the same way you do, at least some of them. The reason 9/11 happened is not because of our freedom or ideals, those people disagree with them but they would never attack us for it. They attack us because of our foreign policy and how some feel Islam is under attack by the United States. Then because we elect the leaders who determine this foreign policy, we are partially responsible for the attack even though you or I never directly hurt anyone and just want peace.
It is very messy issue with a lot of closemindness and irrationality on both sides.
If you want another book that might be good...
Dying to Win: The Strategic Logic of Suicide Terrorism
I haven't read this yet but I have a feeling it might be informative.