I've heard the "Libertarians are one step away from anarchists" argument multiple times before, but I've honestly always found it perplexing. At least with regards to my own libertarian views, government is essential. In libertarianism, the government is the objective enforcement of contract laws and the defender of rights. Without the government, you would have anarchy, which is a rule by force by intrinsically dishonest people resulting in the exact opposite of the upholding of contract law and rights.

That is the _opposite_ of libertarian desires for freedom from the desires of others. Why would any libertarian desire this?

I'm going to speculate, as I'm not well versed in the history of libertarianism, but I suspect it grew out of anarchism inasmuch as it was a righteous rejection of government abuse. You see this occurring today with the Occupy movement; the government has failed and rejected its duties, therefore they reject the government. I consider this throwing the baby out with the bath water.

With regards to the NAP and force, the American founding fathers regarding the 2nd Ammendment did not even believe the government should have a monopoly, but instead the whole of the populace should hold its propensity for tyranny in check with its own force so to speak. This is consistent with the libertarian value of the right to defend oneself. Force is therefore permissible whenever necessary to rectify the violation of one's rights (contract law being subsumed by this). As far as whether violating my (property) rights is an initiation of force, according to the NAP[1] it is:

     Specifically, any unsollicited actions of others that physically affect an individual’s property, including that person’s body, no matter if the result of those actions is damaging, beneficiary or neutral to the owner, are considered violent when they are against the owner’s free will and interfere with his right to self-determination, as based on the libertarian principle of self-ownership.

So at the end, the obvious glaring disparity between socialist and libertarians is whether the right to own property is in fact a right. Socialists as you see here (comments), obviously refuse to acknowledge the assumption of this right. Unfortunately, the natural progression of having no right to own property is the socialist value that everyone else has a right to your own mind, sweat, etc... Or in other words, we are all beholden to the desires of others as all that we own, even ourselves, are community property.

This in my mind is the most unimaginable tyranny of all, and thus I see socialism as fundamentally incompatible with libertarianism.

[1] http://en.wikipedia.org/wiki/Non-aggression_principle