There is no way Kerrey wins in a landslide, and it is far more likely to be the opposite.
Zogby is underrepresenting Republicans because he is ignoring the seismic shift in party affiliation that happened on 9/11. Since he 'adjusts' his polls by party affiliation, he over-represents the Dems.
Take what Zogby reports and take away 3% from the Dems and add 2% to the Republicans and you have something in the ball park.