Who is more violent?

I recently came across this blog post claiming that Sarah Palin (and the right wing in general) were consistently more violent in word and deed than the left. I think that perhaps the author read a bit too much into Palin's words and assumed that she was inciting violent activity. I think maybe she was speaking metaphorically. The author also went on to claim that the right often gets a free pass in the media while the left gets called out for every little outburst.

Oddly enough, this is the same type of narrative I hear from commentators like Rush Limbaugh. He claims that the left often gets a free pass in the media while the right gets called out for every little thing (including, when the media can't find anything real, totally made up stuff). At a different blog, I discovered this post describing how the left is in fact more violent than the right. The post lists numerous cases of both words and deeds of violence perpetuated by the left and contrasts this activity to the peaceful tea parties of the right.
Who should I believe? Clearly both sides have said and done some things they should not have, but measuring which is worse suffers from a classification problem. For example, what is Joseph Andrew Stark, the man who flew his plane into an IRS office? The left paints him as a right-winger and the right paints him as a left-winger. Well, I have actually read his manifesto/suicide note and find it clear that his main beef was with the IRS code, big government, and corporate bailouts, the same stuff that the right complains about. If he was a left-winger, he would be complaining that the government was too small and wasn't doing enough, but he was clearly bitter that there was too much regulation and too much taxation instead. That the second blog includes him as an example of left-wing violence makes me wonder about the other examples listed.
Does it even matter? My stance is that it does not. We can all agree that fringe groups, however one might classify them, sometimes do bad things. I hope we can all agree that to paint an entire movement or party as violent by the actions of a few members (that might not even belong in the group anyways) isn't helpful to discourse and should be refrained from. Case in point: The Tea Parties, which have clearly been a movement against overspending and big government from the beginning, should not be labeled as racist, astroturf, or violent based on the actions of a few individuals (who may have infiltrated anyways). Meet them on the issues and discuss the merits. That's all I ask.