I want to show thumbnail excerpts on my home page. Do I need this plugin or is there a way to do this in Atahualpa?

Thanks

You would add the image as a featured image and also add <img> to Don't strip these tags in ATO>Configure Excerpts.

I tried this and even though some of the thumbnails show up, none of them are the size they should be (150 X 150).

Is there a trick to this? Or is there a plugin that works better?

http://shopwithmemomma.com/

Similar problem here... In my case, when I add a featured image and set the dimensions for thumbnails in the ATO Excerpt settings to 300x200, the thumbnail is 150 px wide. In WP's own media settings, thumbnails are set to 88x88. I don't know why it is resized to 150 :-(

Thumbnails sometimes have to be regenerated if settings were changed.