If the Eagles beat the Cowboys they will not only win the NFC East, but also become the #2 seed in the NFC and earn a first round bye. The Eagles will also win the NFC East with a tie, while also earning a bye if the Vikings lose or tie.
The only scenario that really matters though... is beat Dallas.
Ironically, if the Eagles were to lose this Sunday they could very well find themselves back in Dallas for a rematch the following week. With a win, the Eagles probably couldn't face the Cowboys again until the NFC title game.