Auto creation of thumbnails from Drupal (conversion)

I’m doing a full conversion from Drupal to WordPress. I’ve got all the SQL for the conversion running properly and my demo site looks great except for the image thumbnails. (You might call these the featured images. Not sure. I’m talking about the various sized thumbnails in the home page and the sidebar widgets for stuff like popular posts.)

All of my articles have an image in the top of the article (just so happens that’s how my drupal site was set up. However, they don’t show in the thumbnails in WP.

I performed some testing and I found that if I open a converted article in WP for editing and then click the Update button, the article now shows the thumbnail in the sidebar, excerpts, etc. To me, I’m guessing there are two avenues for resolving this problem;
1. Open/Update all my articles one at a time (NOOOOOOOOOOOOOOOOOOOOOOOOOO!)
2. Find a way to run a batch script to do it.

Any idea if number two is a possibility?

I tried the WP regenerate thumbnail plugin but that didn’t do it. It seems like there is a WP table somewhere that stores the thumbnail information for a post and that’s what the edit/save process is filling in for me.