Do you want revenge? Or do you want to stop terrorism? 
They're not the same thing at all. Over here in the UK, we've 
been being hit by terrorists (the IRA) for 30 odd years (I live
in Brighton which had the Grand Hotel bombed in '86, so 
terrorism wasn't invented on Sept 11). General rumour has it 
that MI5/6 (Rough equivalent of CIA and FBI) have known and
could kill all the members, but don't because (among other 
reasons) they know that the next day, the IRA would be three 
times the size, due to all the sons / brothers /fathers etc. 
who, like you, would be out for revenge. Now some might argue
that the IRA are freedom fighters rather than terrorists
(Englands history in Ireland isn't one to be particularly 
proud of.) Well some would say the same of Bin Laden et.al. The
U.S.'s history round the world isn't always spotlessly clean.
Personally I think his methods are crap. What should we 
conclude about George W.'s methods?
One slightly different argument for why this maybe isn't such 
a good idea. A hundred years ago England were the big boys in 
the playground. Fifty years ago we woke up and realised we 
weren't anymore. A hundred years our attitudes were smug and
arrogant. Divine right (God was an Englishman don't you know?) 
to shove our own attitudes and values down everyones throat 
(We went to war with China to force them to except free trade, 
in particular opium,(the heroin of the day)). Attitudes 
characteristic of empires in the stages of decline everywhere. 
Attitudes characteristic of America at the moment. Folks over 
here don't reckon you're going to keep world hegemony for 50 
years tops if you keep going the way you're going. Which I 
think would be a pity, as I have a lot of respect for your 
country, based on the Americans I've met, and I think you've
still got a lot to offer the world, but at the moment all 
you're offering are bombs, bloodshed and the one fingered 
salute. Well perhaps not, we'll see in fifty years won't we.
P.S. sorry about all the brackets.