Mulroney realized that he needed to get Quebec and Ontario to win, that's why he moved to a riding in Quebec, even though he spoke very little French. Harper should really do the same, but with so many Bloc members there he'd risk losing, not the same times I guess.
Harper is trying to take Ontario and Martin is trying to maintain it. No one cares about the East (Newfoundland 6 votes /Maritimes 24 votes) or the West (Praries/BC 24 votes). They only care about Ontario worth 24 votes and Quebec worth 24 votes. The Conservatives have most of the West and that won't change soon and the Liberals have most of the East and that won't change soon. Quebec is mostly Bloc, which only leaves Ontario as a battleground.
If Duceppe leaves the Bloc Quebecois it is possible to open up Quebec again. BUT, unless something major happens it'll come down to buying votes, whether it be the NDP, the Liberals, or the Conservatives. In Ontario you'll hear all three parties offering that province everything, while Saskachewan, Alberta, Manitoba, British Columbia, New Brunswick, Prince Edward Island, Nova Scotia, and Newfoundland get no offers.