I can't believe how fantastic the VirtualLab Data Recovery program worked!
I thought I'd lost all my photos, but I recovered 95%+ of them. I feel like a complete Wally, as I lost the photos in the process of backing up onto my new external hardrive. I re-partitioned the drive on my macbook, thinking that I'd backed-up on to the external, when I found only empty folders (I didn't verify).
So I had to recover from the re-partitioned drive.
I think the trick is once you've discovered the mistake, don't interact with the computer until you're ready to do the recovery.
Thanks for the great software.