Okay I'm not going to answer this just yet (I only slept four hours and intend to get more), but the question is not so much about God and a rock as it is about whether or not God can create something greater than Himself
And the answer to that question is yes.
highwaystar101, you will take note that in Genesis 1 God moves upon the surface of the water before he actually creates anything - the universe was there before God walked on it. Neither one necessarily predates the other, but both of them predate the time when God arrived in the universe.
A strict reading of Genesis depicts God as a shaper, not a creator, in the strictest sense. He is a sculptor working with the clay of the universe.