Assuming all republicans would vote for Bush and all democrats would vote for Kerry, had the percentage of republicans and democrats been 41% and 35% in Newsweek's most recent poll, Bush's lead would be 50%-40%. I don't put any stock in any of the polls other than the one on November 2.
"Assuming all republicans would vote for Bush and all democrats would vote for Kerry"
Actually I think it was 93% of Republicans for Bush and 87% of Democrats for Kerry. That would only strengthen your conclusion, though)