Understanding Entanglement and Parallel Computing in Quantum Computing

[KrevinL]

I'm a bit confused about entanglement with regards to quantum computing. I'm not an expert by any means, but I've been reading around about quantum computing and was confused about something.

I've read that, you can't directly observe a qubit, because if you do the wave function will collapse and it will be no better than a classical bit, so experimenters are using entanglement to get information about other qubits, enabling them to do parallel computing on a single qubit. However I'm failing to see how a qubit can still perform parallel computing, if once one qubits state is observed, both entangled qubits wave functions collapse. So I'm thinking that entanglement just gets you 2 classical bits, with the effort of only measuring one.

Can anyone tell me how this enables parallel computing within a single qubit?

 

[KrevinL]

Also, how is a quantum computer set up to perform a calculation like integer factorization? I think it has something to do with initializing a qubit with some wave function, but I'm not sure how this end up calculating anything.