For my understanding, only random thing in the world is decaying of atom. Google for Schrodingers Cat, its simple "theory" of this process, even i can understand it..=)
Computers random is, like Skuzzy said, an algorithm, that picks one of its variables from computer clock. The randomness follows a bezier curve, but isnt apparent if your sampling rate isnt exactly evenly spaced. Ie enter press per every second hardly is exact enough to bring up this pheomenon..
God knows how many different states a computer clock can have in one second, but i think its somehow related to the MHZ of your CPU.
I have only faint memory of this issue in my mind and i might be totally off the base here. So, forget what i said and do a websearch..