I think I solved this one. My plan was I would just keep installing free software and updates from the Microsoft site until something else needed the VSTA plugin and installed it for me. I'm not sure if I need all of these steps, but what I installed was:
IE8
Silverlight
then went to update.microsoft.com and had it install everything it wanted.
and then VSTA worked InfoPath was visible in the Add or Remove Programs control panel.
Now to replicate this on another tablet ...