Whether or not Howard Dean's much-discussed comments about Republicans are accurate, Peggy Noonan is right that attacking "Republicans" is a counterproductive rhetorical strategy for the Democratic leadership.
The Republicans intuitively understand this point, which is why they focus their attacks on "liberals," "liberalism," and individual Democrats -- but never on the Democratic Party per se.
It's not the Republican Party that is the problem: rather, the problem is ideologues who have hijacked that Party. The political and electoral goal for the Democrats should be to attract people who consider themselves "Republicans," but are disgusted by the leadership and populist fervors of the Republican Party today. Attacking the Republican Party as such works at cross-purposes to this goal.
With this in mind, the Democrats should focus their rhetorical barrages not on "Republicans," but on "right-wingers," "reactionaries," and "wingnuts" -- starting with the right-wingers who are attacking Dean. Moreover, to underscore the point: the attacks should focus on "right-wingers" -- not "conservatives." Lots of people are self-identified conservatives, and you may well want some of them want to vote for you; on the other hand, lots of these self-defined conservatives dislike right-wingers, and everyone knows that the Republican Party is the Party of the wingnuts.