This is fascinating. Here's a comparison video of Bush at a debate for the Texas governorship in 1994 and Bush vs. Kerry 10 years later. The difference in his cognitive abilities is striking.
I paid a lot of attention to this race in 1994, being 16 and just becoming politically aware. I remember Bush the gubernatorial candidate a little bit, and I remember people being pretty impressed with him (admittedly, in a very conservative town). One thing I definitely remember is that people had some reservations about Bush, but it was never that he was stupid, and you'd think that criticism would've come up seeing as he was going toe-to-toe with Ann Richards, who at least presented herself as exceedingly polished and sharp.
Perhaps my faint rememberings of his governorship (or at least his '94 campaign) are why, even though I joke about it, I still sometimes resist the argument that W has been such a disaster because he's stupid. I really think that W is still the man in charge, and that he's going along with the neocons because he is one. He totally buys into that ideology. The reason he has such a puppet persona, in my opinion, is because as long as people believe he's being pulled this way and that by various unseen hands (2 of them being Dick Cheney's, of course), they can hold out hope that maybe he'll wake up and boot out the neocons and set a new course for a less disastrous, if still mediocre, end to his tenure in the Oval Office.
Read my lips, folks: Na. Ga. Happen.
Update: Here's the video: