According to Einsteins theory of relativity, you cannot travel at the speed of light as it requires an infinite amount of energy to do so. The only way to acheive greater then light speeds would be to use the "star trek effect."

"Perhaps the biggest advantages of the gravitational engine I describe on another page is what happens when you put a negative and positive one together and use them to both propel an aircraft (Fig 6). If the negative engine provides additional power to take account of your mass the two engines will cancel each other in the centre of your craft and your mass will then in effect be zero"

with "zero mass" you would then be able to acheive not usualy normal effects, as it would take infinitly small amounts of energy to create extreme effect, like greater the light speeds

"According to Special Relativity kinetic (movement) energy is related to your speed and your mass. The faster you go the higher your kinetic energy so it follows that this energy need to come from somewhere. As you approach the speed of light this kinetic energy level rises sharply giving you very high energy needs if you wish to reach such speeds. With two gravitational drives however it is possible to to cancel your mass out so it becomes zero and if you use a zero mass value in Einstein's formula your kinetic energy is zero irrespective of speed. If your kinetic energy remains at zero you can then travel at what ever speed you wish - even at speeds faster than light! It is the high values of kinetic energy that prevent you from travelling at light speed, remove your mass and the light speed barrier disappears."

now the problems of this
problem 1: having positive energy on one side and negative on the other would cause the zero mass effect, in the exact middle of the ship. Thus, one side would have mass and the other would have negative mass. You might be thinking how this would matter, well, once you have reached near light speeds to much kinetic energy would be acting apon the positive side, while none on the other side. It would then pull your ship in half.
problem 2: now hypotheticly you get your ship to stay together at light speeds, you, nor anything else onboard, would want to move, moving would upset the equilibrium of the two generators, thus creating more then 0 mass, which would basicly crush your vehicle and slow it down to less then light speeds.
problem 3: Now, say you solve problem 1 and 2, your ship would be perfectly able to do greater then speed travel, but... What happens to the generators? the generators would have mass to them, thus it would be unable to reach light speeds.

Advantages to this method
advantage 1: With this method of light travel and "zero mass," the amount of acceleration which would normaly be absurd will be fine for this. Your acceleration is only limited to the capicity of the generators you are using, meaning 30Gs of acceleration would not effect the human body or anything else at all, for that matter, you could live through accelerations of infinate porportions, the only limitions would be your generators.
advantage 2: This method actualy uses surprisably small amounts of energy to make happen, as your mass is "zero," there isnt much for your generators to push.

heres the figure


Heres my source http://www.blachford.info/quantum/fastlight.html

NOTE:
"When I say zero mass I don't literally mean that. You will always have mass but it will appear to the universe that you have none.  i.e. you would put zero into the relevant equation (the Lorentz Transformation) and it will show there is no incerease in energy necessary."

Some of the weird science stuff has been removed, it was previously left here for the humour value.
Some people evidently don't have a sense of humour...