Id probably go Helu. Hes gonna get you rushing and receiving yards. I didnt see the Redskins game/highlights but I assume they give him a lot of screen passes.
As for the D, I know Washington is tempting but Miami's offense is picking it up a bit. Freddy Jackson had a field day on Washington and I think Reggie Bush could do the same especially if Miami runs those sweeps and screens.
Arizona is generating nothing with Kevin Kolb as QB. Their back up out performed him and theyre on the road against a team that should be able to beat up on bad teams. Id go Philly there.