I'm probably not giving up on it. I'm just going to do it a folder at a time and BACKUP BACKUP BACKUP. What really ticks me off is having to reindex 600 files at a time. Argh.
So now I've successfully used Calibre's html2oeb to create a directory with an opf file so now I can use the for %a (in *.mobi) do conversion.
Now I'm trying to figure out how to use a command line command to turn opf back into prc so that I can do all folders at once

If you know how let me know!! Thanks!