davorg is right. Computers (as they now exist) can never produce a truly random number. This is because, as Bruce Schneier puts it, "Computers are deterministic beasts: stuff goes in on one end, completely predictable operations occur inside, and different stuff comes out the other end." This enables back-computation.
Computers need humans to be truly random. They do this by having humans entropize their entropy pool with mouse movements, thus enabling the creation of Truly Random numbers.
redmist
Silicon Cowboy