Antimatter Spacecraft

I read this article: http://science.howstuffworks.com/antimatter2.htm
Antimatter is like normal matter, except that the charges of the particles of antimatter are reversed, so that an electron is positive instead of negative, etc. Upon contact with normal matter, 100% of the mass of the collision is converted into energy, which makes it an extremely powerful potential energy source. However, extremely high energy particle collisions are needed to produce it, so you need giant accelerators, called atom smashers, to produce it. We can only make extremely small amounts of antimatter, so the amount needed to produce a significant amount of energy would cost trillions of dollars. However, there are plans to build reactors to specifically produce antimatter, which would lower the cost for the same amount to a few thousand dollars.
NASA researchers have produced plans for a spacecraft powered by antimatter. It would take 11 months to reach Mars with current technology, however, this spacecraft could make the journey in 1 month, making travel tto Mars practical for the first time. This spacecraft would focus the energy from a matter-antimatter reaction out of a nozzle to produce thrust. I would say that this spacecraft will be possible within a few decades, or possibly less.