Many historians (read: people who know more about the past than you do) agree that the intention of the second amendment was not to protect an individuals right to own guns, or to provide the people with means to overthrow the government. In fact, they feel that such an attitude during that time would be silly to consider. At the time, individual rights were not a pressing issue on the mind of the public. The major concern in government was the issue of state vs federal power. Because of this, most people were concerned with the ability of the state to protect them from the national government, not in their individual right to bear arm or overthrow the government. This was demonstrated by the Whiskey Rebellion of 1794 where farmers in Pennsylvania formed to carry on a revolution against the government. However, their actions were denounced uniformly by the people involved in the drafting of the Bill of Rights which clearly shows that they did not feel the public had the right to take up arms against the government.

For an excellent in depth look at the true meaning of the second amendment, I recommend the book "Whose right to bear arms did the second amendment protect?" by Saul Cornell (a former history professor of mine and all around smart guy). It contains six essays by historians each presenting their own point of view on the isue.