Jack Black as a monk?

From the previews I've seen, Nacho Libre looks like it will be a pretty funny movie, but I have a couple worries. In the movie, Jack Black plays some kind of monk who moonlights as a wrestler to raise money for the orphanage where he works. I don't think there's a problem there, but some of the previews make it look like Jack is in love with the sister who also works at the orphanage. That would be a problem.

However, the makers of this film are the people who created Napoleon Dynamite and I think that they have demonstrated their ability to make a funny and clean movie. Hopefully Nacho Libre turns out the same way. The clips that I've seen look extremely funny and visually beautiful (like Napoleon).