[Arnabas]

I just assumed that while the CPU was destroyed in T2, some of the information gleaned from its study survived. As for the bit about the internet, I just took that to mean that after being activated, Skynet was now everywhere. Any computer anywhere was now a part of it. Skynet would certainly ensure that some part of itself survived when the bombs started falling. As for the virus... That is a bit harder. Perhaps Skynet, in some previous testing, was linked up in a limited capacity to the internet, where it released a timebomb virus that would eventually activate and lead to the events of the film.
Anyhow, I would have liked if they had included one little thing: When listing the secondary targets for termination, they should have included Reese. I thought it would be cool if John had to save the life of a young boy who would grow up and eventually go back to save *him* before his birth. It could have been neat having him be friends with a young boy, who in actuality is his father...
Anyhow, I liked that they got the story back on track... I always felt it was wrong that they had been successful in T2... There is no way to change things. In effect, all they did was create a divergent reality.