He was chosen by a consensus of wealthy and well-connected movers and shakers in the GOP establishment as someone who could

1) connect the religious and business bases
2) have a familiar name
3) have automatic credibility as governor of a large state
4) and most importantly was pliable to and comfortable with their commands

Cheney was chosen for him as vice president to make sure he did what they expected

Once a candidate, an undemanding media conveyed him mostly as his handlers wanted him to be seen, and when the going got tough he had the money and the political brain trust (plus in South Carolina the right state) to push to the nomination

Then he had the luck of a combination of circumstances (including an underwhelming Al Gore and the presence of Ralph Nader; the Supreme court; his brother as governor of Florida) to get to the White House.

Except for the invocation of "luck" in the last paragraph (it certainly wasn't luck of any sort that conservative Republicans dominated the Supreme Court, and we've seen that Nader receives funding from the GOP), I think that's pretty accurate. My recollection, which I haven't so far been able to verify via online search, is that very soon (very soon) after Bush started being bruited as a possible candidate, he had a warchest that was extremely large, an unprecedented amount of money. For that to happen, people had to have agreed in advance that Bush would be their man, in my opinion.

Incidentally, Kevin's question comes in connection with Jacob Weisberg's article about Bush in Slate, The Misunderestimated Man. I'm sure most people will have already read it, but, if not, here's your chance.