Wow, it works GREAT, thanks!!!

For icons, I was thinking of using a few from this free set:
http://www.silvestre.com.ar/?p=4
the 128x128 or 48x48 (or 24x24, thought they might be a bit small) icons:
refresh: actions/reload.png
download pics: actions/filesave.png
select all: actions/list-add.png
invert (a tough one to find an icon for): actions/list-remove.png

And, just maybe,
EDIT:http://aldwin.us/imgloadbar.gif
(the image really comes from ajaxloader.info but I just realized the link had hotlink protection.  So here's a friendlier link.)
for when reading/downloading?

Also, I noticed that this line was not working:
So when I replaced it with this line it worked fine:

And finally,
ESC still exits -- is there any way to change it to a less guessable key?

EDIT: Oh, and I had another idea (ugh, I'm so embarrassed that I'm asking you so much): some users might try to click on the picture to select it.  Is it possible to make a click on the picture check/uncheck the checkbox?

It would probably be a good idea so the person doing the downloading can make sure they're downloading the right pictures.

Yes, picasa works well to import (even from memory cards), as does Adobe Bridge Downloader (what I personally use).  But, neither has a simple enough interface suitable for a photo downloader kiosk.