Matt Yglesias and Michael Cohen, both of whom have been asking very tough and smart questions about the U.S. mission in Afghanistan, doubt that our copious care  in avoiding civilian casulaties--as opposed to the Soviets' savage tactics--could make the difference between victory and defeat there. Quoth Matt:

Maybe. That said, I don’t really think it’s a fair comparison. The Soviets had to fight a Mujahedeen force that was receiving open and full-throated support from Pakistan and Saudi Arabia, plus substantial financial and material assistance from the United States. We’ve had our problems with Pakistan playing footsie with the Taliban, but nothing like the level of open support for anti-Soviet forces that the Russians had to contend with. And you’d have to assume that our efforts in Afghanistan would be badly complicated if the government of China decided to adopt the Taliban as its proxies.

Fair point. On the other hand, it's not as though the Taliban don't have own well-heeled patrons. Just last week, Richard Holbrooke complained about the sustenance the Taliban gets from Gulf Arab states--prominently including Saudi Arabia (though not, admittedly, from the official regime, but rather "individuals carrying suitcases with money," as Holbrooke puts it.) But that's presumably not the same as the superpower (i.e. American) support that the anti-Soviet mujahideen enjoyed.

P.S. Cohen argues that "[s]imply because the Soviets targeted civilians and lost the war does not mean that the US protecting civilians will win the war." I agree! Didn't mean to imply otherwise. Just thought the contrast between the two armies is important to consider when drawing historical analogies.