There really isn't much difference between Objectivism and Libertarianism. At its best, Libertarianism is the political implementation of Objectivist ideas. Objectivism is a moral philosophy on how one should live one's life. Other moral philosophies generally come from religion (i.e. God determines what is right and wrong), but Objectivism is derived from reason and observed reality. And Objectivism is the only moral philosophy that places the individual as paramount. All others (as far as I know) allow that society may sacrifice an individual for the good of others (i.e. Socialism).
The problem that many Objectivists have with Libertarians, and the reason Ayn Rand didn't like Libertarians, is because Libertarians usually arrive at their conclusions for utilitarian reasons. For instance, an Objectivist would say that the income tax must be abolished because it's wrong to steal. A Libertarian may say that the income tax must be abolished because we need to decrease the amount of revenue that government receives so we can decrease spending, because it's better for the economy, or for any number of other reasons. But all of these reasons are based on the result of getting rid of the income tax (it's better for society to not have it than to have it). Objectivists have a problem with this because the Libertarian that believes this will change his mind if he is convinced that the result of having the income tax is better than not having it, whereas the Objectivist will still be against it because it's morally wrong, independent of whatever result it may have.
In short, Objectivists see Libertarians as having many of their same political beliefs, but no moral foundation supporting those beliefs. For those that are Libertarians, but were former Republicans or Democrats and became Libertarians because they see it as simply an alternative, or they see the waste in government, these are the ones that Objectivists disapprove of, because these people are prone to sway back and forth. They have no innate belief that initiation of force is simply wrong, and will approve of the initiation of force (not to be confused with retaliatory force, which is perfectly acceptable to Objectivists and philosophically-based Libertarians) if they belief the result of that force will make an overall improvement.
Ayn Rand is by no means a perfect person, but the Objectivist philosophy is logically sound. I would highly recommend learning more about for those that aren't familiar. And for those that are religious, I understand that it can be extremely difficult to accept the idea that there is no god, even with a mountain of evidence pointing to that conclusion.
For a better understanding of the ideas, you can get a brief introduction from this series of videos. It's not specifically about Objectivism, but about Collectivism vs. Individualism, so it talks about the differences more than promoting them (but it does seem to be slanted in favor of Individualism):
http://www.youtube.com/watch?v=dJqSsrFDiSA
http://www.youtube.com/watch?v=qXOrJtn1h2M
http://www.youtube.com/watch?v=BOUS6OalV2I
http://www.youtube.com/watch?v=_AgcVNzObWE
http://www.youtube.com/watch?v=VKPPe78pX5w
http://www.youtube.com/watch?v=F5_N86Pblj0
And of course, there's the classic "Philosophy of Liberty":
http://www.youtube.com/watch?v=muHg86Mys7I
BTW, we're not really assholes.. I think a better word to describe many of us would be arrogant, or at least we have the appearance of arrogance. But that's because we have a solid philosophical foundation on which to base arguments. If you put a bunch of us in a room together, that arrogance tends to go away since we're all pretty much on a level playing field.
