I would say you are wrong on this point. People do not in general vote VP.
If you are correct, she is bringing more people to JM than she would be losing.
Palin has energized the conservative base. Candidates who draw crowds in tens of thousands are not driving people away.
Now, why might this be so? The media jihad against her has been brutal, but one "hit piece" in particular seems to have done a great deal of damage: Katie Couric's interview on CBS. Palin came off sounding confused and ill-prepared... but here, my friend, is why:
http://thepinkflamingo.blogharbor.com/blog/_archives/2008/9/26/3902581.html
Or, go Here.
I urge you to read this article. It points out how Palin's words were intentionally edited and presented out of context by CBS.
Surprised? I'm not. I'm only surprised that the McCain camp have not called them out yet.