Hi there

I found the posts here interesting as am also keen to resize many photos all at once. I thought I'd go have a look around Google, and am pleasantly amazed at what's out there.

I found this site

http://batch-image-resize.qarchive.org/

and they have 50 different programmes to download that resize images in batches for you. There is a fee for most of them, but there's actually some free ones there too - they have comments from users on how effective they found the resizers to be.

An excellent, helpful site, I think.