Conventional wisdom has taken such a beating in this campaign that setting expectations for today's primary continues to confound the experts. The only thing everyone can agree on is that, given the makeup of Pennsylvania - an older population with a significant blue-collar constituency and a sizable proportion of Roman Catholics - Sen. Hillary Rodham Clinton should win the popular vote. But as Democrat Matt Bennett put it, the candidates are like publicly -traded companies that need to hit an earnings target to lift their stock price.But just what are the targets? Some say Clinton needs to win by 10 points - which was her margin in Ohio last month. Others say eight points. Some say, given the amount of money Sen. Barack Obama is spending on television ads, anything over five points would be a respectable victory for Clinton. Staying within five points would give Obama the opportunity to assert that he overcame a state whose demographics tilted heavily to Clinton.But the margin in the popular vote ultimately will be secondary to how Pennsylvania affects the battle for pledged delegates. Pennsylvania is the biggest remaining prize on the calendar, with 158 pledged delegates. Clinton badly needs to make up ground in the delegate fight and, given the way they're distributed, that could be difficult.In the words of one Democratic strategist, the popular vote margin is a "feel-good barometer that may play out over a few days and longer if there is a big win, but then we will be on to the next contests. Ultimately, the second indicator [delegates] is more