Here is how the Dallas Cowboys still make the playoffs in 2010

Lets say that Dallas runs the table for the remainder of the season. That will put them at 9-7 with two critical wins over the Eagles and one over the Redskins. As of right now Dallas is last in the NFC East, here is a low down on how it stands:

Giants 6-3
Eagles 5-3
Redskins 4-4
Dallas 2-7

So if Dalls wins out, that is 2 more losses for the Eagles and 1 for the Redskins. For Dallas to trump the Eagles in the division, the Eagles only need to lose 2 games other then the losses to Dallas. Out of the 6 games (not including Dallas), 2 losses would tie them with Dallas but they lose the tie breaker since Dallas is 2-0 against them. This is the easiest scenerio out of the other teams since Dallas can win the head to head matchup. Here is the remaining schedule for the Eagles:

@Redskins
Giants
@Bears
Texans
@Dallas
@Giants
Vikings
Dallas

For the Skins to fall behind Dallas it would need to lose 3 games out of the 7 non Dallas games remaining. I am just playing it safe here and saying they need to finish the season at 8-8 or worse. There may be a way for them to finish 9-7 and still lose out to the Cowboys due to division/conference records, but 8-8 ensures they can't win the division. Here is the rest of their schedule:

Eagles
@Titans
Vikings
@Giants
Bucs
@Dallas
@Jags
Giants

Giants may be a bit more of a stretch. They either need to lost 5 of their remaining 7 games or lose all 4 against the division rivals. Losing against the Skins and Eagles would put them at 9-7 but Dallas would win due to conference record. Here is their schedule:

@Eagles
Jags
Redskins
@Vikings
Eagles
@Packers
@Redskins

Now of coarse this is all moot and gets even more complicated if Dallas loses 1 game, but this season has been a weird one for the NFL and who knows, maybe they still have a chance at 8-8 :)