"Those people are still living in the 10th century or earlier.  It’s a tribal situation much worse than Iraq. … Afghanistan is not called the graveyard of empires for nothing." - F P 

 Anyone understanding the complex history of Afghanistan will realize that peace can not be achieved in 5 years or 10.  Other posters have pointed out rational reasons for America’s presence in Afghanistan, yet at what cost of lives to try to insure peace in a region of the world that has never known stability.  I would wager that most veterans of Iraq would ask the question we all [must] ask, "Why are we there?"  And, according to some reports of military men and women who have already served a tour of duty in Afghanistan [witnesses of fallen comrades], many have become weary, questioning whether military intervention is the appropriate.

Osama bin Laden is very important.  Supposedly the family cut him off.  Supposedly.  In Islam a family cannot go against the wishes, or the will, of the father. And bin Laden shares in the fortune and the income from the fortune.  The only thing worse than a terrorist you cannot locate is a terrorist who has untold millions of dollars, perhaps hundreds of millions of dollars, at his disposal. He has the means to buy a nuclear weapon. So far he hasn’t found one. Be assured he is looking for one. 

He is not the only terrorist in the family.  Two of the sons-in-law in Boston who were whisked off to safety after 9/11 had been convicted of terrorism in Jordan.  Which the FBI knew when they put them on the plane.

Bin Laden is not the wealthy and powerful manipulator he once was.  The US and other countries have done well enough at freezing bank assets and blocking donation sources, that Al-Qaeda is now reduced to begging for money.  Bin Laden’s second, Ayman Al-Zawahiri, has been out beating the bushes for donations and not coming up with much.  So if Bin Laden still has some accessible millions somewhere, maybe he should help out his little buddy by writing a few checks.  But I think you will find he has fallen on hard times.

The Taliban is currently much better financed than Al-Qaeda, and significantly, since 2001, they have bitterly blamed Bin Laden and the Arab fighters for their loss of power (true… but also their own fault since they wouldn’t turn him over when we asked nicely).  What’s good about this for us is that if the Taliban are co-opted back into Afghan government, they are NOT bloody likely to invite Al-Qaeda or other meddling foreigners back to their table anytime soon.

Now, before anyone harps on the current consideration of inviting the Taliban back into the Afghan power circle:  co-opting old enemies back into government is a longstanding and proven method of re-establishing stability, and if done well, can also make allies of former enemies.  Witness:  after WWI, the Allies left the Germans on their own and saddled with war reparations costs in a destroyed country.  Thus followed WWII.  After WWII we got smart and enacted the Marshall Plan with great results for Germany, Japan, and the whole world. On a smaller scale, we did the same after invading Panama in 1989; the Panama Defense Forces were dictator Noriega’s instrument, but those guys - minus the worst-offending leaders - went right back to work as the Panama National Police, and things were normalized within a couple of months.  It was practically seamless.  In contrast in Iraq - Paul Bremer completely disbanded Iraq’s security forces to start over from scratch, barring anyone who was previously a member of the Baath Party - which was pretty much everyone who had any expertise in anything at all. Predictable results.