The good news for the Rangers is that the last time they played Philadelphia, on March 14, the Flyers looked undisciplined and overmatched in the Rangers' 3–1 victory. The bad news for the Rangers as they head into their crucial home-and-home against the Flyers is that Sean Avery, who was largely responsible for that March 14 victory, isn't likely to be in the lineup.
To recap the position the Rangers find themselves in: They control their own destiny, in that they'll clinch a playoff spot if they win tonight and Sunday, and win at least one of those games in regulation. (Technically, they could still pass Boston and Montreal, but not Philly, if they won both games in overtime, assuming Boston, which has two games remaining, and Montreal, which has one, lose out in regulation. But that's an unlikely scenario.)
Last year, you may recall, the Rangers clinched a playoff spot on Garden ice with a dramatic win over Philadelphia. (If you don't remember a lot about that game, you might at least remember this save.) This year, they can't clinch on Garden ice. If they do this, they'll have to finish it off in hostile territory. Last time the Rangers were in Philly, they stood idly by whilst Marian Gaborik got his ass kicked. Maybe they'll lose tonight, and it'll all be moot. But if Sunday's game ends up deciding the last spot in the playoffs, it's unlikely they'll go down without a fight this time.