Thanks for the ' format filter' option!
I will definitely delete them from within calibre next time like I should have.
I fiddled around with some settings and found in the Advanced Preferences a "check database integrity button".
When I clicked that a whole lot of invalid entries got deleted.
The handful that were left had no information for file size, so I could easily delete those too by sorting on size.
After an afternoon of fetching data from server and downloading covers I'm left with 750 books to read. Now all I have to do is wait for the Kindle DX to arrive....*runs back and forth to mailbox impatiently*
If it syncs like I think it will, I'll donate