Get ready for a " That '70s Sho w " flashback this week when Wilmer Valderrama joins his old co-star Laura Prepon on her NBC comedy, " Are You There, Chelsea? " It's been six years since we vacated the Formans' basement -- and now that the funny-smelling smoke has cleared, we can see that some of the cast have since rocketed to superstardom. So throw on some polyester and fire up the 8-track as we take a look at what the "'70s Show" cast is up to these days.