quantum computer + entanglement

What is a quantum computer? http://curiosity.discovery.com/question/what-is-a-quantum-computer "A quantum computer, however, computes on an atom and not silicone -- in theory, as we're still a long way from seeing an actual quantum computer. The idea is that a quantum computer creates a quantum state in which quantum bits, or qubits, can exist." How is quantum entanglement useful in computing? http://curiosity.discovery.com/question/quantum-entanglement-useful-computing "...quantum particles cannot be observed without being altered -- so how do you read the value of a qubit without changing it? Scientists use their knowledge of entanglement to indirectly observe the value of a qubit. When two subatomic particles become entangled, one particle adopts the properties of the other. Without looking at the qubit itself, scientists can read its value by observing the behavior of a particle with which it is entangled."