Aside from allowing the Conservatives to cue their poll questions, the problem with all this leadership focused polling by the media (such as the Globe poll by Strategic Counsel) is that it is misleading. Leadership preferences tend to follow partisan switches not lead them. This Paul Wells post nails it.
Indeed, Joe Clark in 1979, Jean Chrétien in 1993 and Dalton McGuinty in 2003 were all deemed less popular than their opponents at the outset of their campaigns but won anyway.
In fact, I can't believe that most Canadians have any firm view of Dion who has held his position less than three months. Quebeckers perhaps but not English Canadians. This entire discussion amongst the pundit class strikes me as a classic case of Ottawa Rideau fever.
The Liberals have real liabilities going into the campaign - organization, money (meaning an ability to respond in kind to the Tory ads), division on issues (Afghanistan, extending the anti-terrorism law, etc.) but so-called weak leadership impressions at this stage aren't among them.