|MadSci Network: Physics|
You've just come up with a very good reason why it's impossible to accelerate any object with non-zero mass all the way up to exactly the speed of light. Other reasons: such an object would have infinite energy and infinite momentum.
If you're not satisfied with those explanations, consider this: if you were on a bus that was travelling the speed of light, you would not be able to walk, think, or do anything, because for you time would be frozen! You may have heard that time slows down on clocks that approach the speed of light. Well, on a lightspeed bus, viewed from outside, time would actually stop! From your perspective (on the bus) the rest of the universe would shrink down to an infinitely thin pancake, and you would be everywhere at once -- you would appear to be travelling at an infinite speed. So in the direction you were travelling there would be nowhere left to walk.
If this doesn't make sense, it's because the premise is impossible to begin with. Here are some relativity links.
Try the links in the MadSci Library for more information on Physics.