If the Bruins do win the Stanley Cup next month, their first since 1972, the engraver might be directed to etch one bold asterisk next to their names on the big silver trophy: "* — Accomplished with one hand tied behind their backs.'' Such is the state of the Boston power play, which actually scored a goal last night (click here for the "Hallelujah Chorus'') in a 5-4 loss to the Lightning that set up Game 7 of the Eastern Conference finals tomorrow night at the Garden. And it was the power play that remained the biggest single difference — and for the Bruins, the largest embarrassment — between these two Cup-dreamin' teams.