I think whoever McCain picks as a running mate is crucial. I heard today that Condoleza Rice wouldn't rule out a VP offer - I don't know if she would be good or bad for McCain.
Considering that McCain has been trying to distance himself from the Bush White House....Rice as VP is a shitty idea. Why tie oneself to anything connected with toxic waste?
As for the poll, is this asking who I want to be President, or who I think will win?
If its McCain/Hillary, McCain will win.
If its McCain/Obama, Obama will win.
EDIT - People voted for Hillary?