At the risk of reiterating others thoughts, yes, computers are intelligent, but no, they can't think for themselves. No thought process is carried out by a computer, but rather it performs how it is programmed to perform. If you program a computer to say that (4*0=9) and it spits out, "Bullshit", then you could argue that it can think.

A computer only knows to the extent of its programmer. It doesn't go through a process of thinking to get a final answer. It just goes through the steps of the program and spits out pre-programmed results from formulas given, set responses, etc. It doesn't have human qualities beyond that.