The second amendment is somewhat ambiguous as to the specific types of weapons a citizen may own by merely stating one has the right to "bear arms". Much law is written this way because it leaves room for further expansion and interpretation as time goes by.
To answer your question, Simon, I do think that if we could correctly interpret the Second Amendment as it was intended (to avoid a monarchical rule such as the new nation had just escaped from) then yes, citizens would be allowed to own tanks, rocket launchers, missiles, etc. Obviously, your point that the SA is antiquated due to the development of weaponry never fathomed at the time of the founding fathers is a good one and a valid point because it isn't possible for any citizen to own most of the weaponry it would take to stop the US government should the government decide to, oh I don't know, let's say go SS and round up a race of people for death camps? It may sound far fetched, but the possibility of this occurring most likely scares more citizens than the threat of Joe Hillbilly shooting them.
Here's my personal take on this--I do believe in better gun control, but private ownership is an important thing to so many Americans that it shouldn't be abolished.
In today's world, technology/computers/hacking is really one of the most powerful weapons both for protection against a corrupt government and for the governments protection. But that's just how I see it.