Switched from PC to Mac, how do I get Now Playing List to Show Back Up

You need to buy Toast 8 if you want to use TTG.

I can get files off of the tivo, I just can't re-watch on the tivo what I have taken off.

You need to enable video transfers in Tivo Desktop. Go to System Preferences and command click on the Tivo Desktop. This should add the hidden video tab. Enter your MAK, the location of your .Tivo files, and the Name. Stop and Start Tivo desktop and you should see your files. You will need to command click the Tivo Desktop Preference in order to get the video tab to redisplay in the future, and to start video transfers if you have stopped the Tivo service. I think you can enable from within toast too but I don't know the steps.

Here's a thread possibly related to your issue, including some theories on its cause:
http://www.tivocommunity.com/tivo-vb/showthread.php?t=369019

Post #5 refers to your issue, which appears to be related to a larger problem with Toast, TiVo Desktop for Mac, and 9.1. Did TiVo Desktop for Windows have a update recently for a change in metadata that TiVo Desktop for Mac did not?