Of all the candidates for quantum information media, silicon (Si) is the most appealing. Si-based quantum information processing could exploit the enormous investment in Si chips made by the computer industry. A Si-based quantum chip may be able to talk easily to standard computer chips. Furthermore, quantum information can be encoded into nuclear or electron spins of dopants (e.g., Phosphorous = P) or as charge qubits whereby one excess electron is shared between two dopants. We will study Kane's original proposal for Si:P quantum computing, wherein quantum information is encoded into the nuclear spin of P. Then we will study the sophisticated Australian "update" of Kane's scheme. This scheme aims to build a Si-based quantum computer wherein quantum information is encoded into the spin of P's outermost electron.