We currently store anti-matter in a HUGE (and by huge I mean football fields in diamter) circular tube. They speed around it in a vacuum(sp? I never can spell it). E=MC^2 like WW said. C=the speed of light which is an amazingly huge number ...now squaring that adds insult to the injury. Let's say we had 50 pounds of that shit ...boom! =D.
Anyways, antimatter is the most powerful method we have right now to approach the speed of light, isn't it? I was watching a show on space propulsion and it said that antimatter explosions could possibly send ships at half of the speed of light. Now I'd like to see the ship that could take that kind of force and survive, though =P.