Obviously, we've all got a "win and your in" mentality - we want to win out. But here's the simplest & quickest scenario, to get to the playoffs, and it's pretty clear.
If the Jags beat the Raiders & the Colts, and Houston loses either of the next two games, the Jags are Division champs with two weeks to go. The Washington & Houston games become meaningless at that point.
Here's how, in case you question the math. Jags win the next two, they finish no worse than 9-7. Colts finish no better than 9-7, and lose to the Jags on the tiebreaker.. Houston loses, and they're no better than 8-8 to finish.
Anything beyond that, I'm not playing with math. :)
(BTW, great NFL what-if tool: http://espn.go.com/nfl/playoffs/machine)