I linked to this presentation in the thread on MG Flynn's report a couple of weeks ago.

Rex,
It seems to me that it is entirely possible that neither side can win: that the international community cannot defeat the insurgency or build a stable, functional, Afghan government that can assure security and exercise effective control over large parts of the country, while the Taliban cannot (given both their ethnic and sectarian opponents, as well as rivals within the Pashtun community) capture Kabul as they did in September 1996.
That's pretty much where I've been for a couple of years now. Personally, I think Afghanistan is ungovernable in its present state. It's frankly depressing.