Michele,
The easier the better I say.
Using Photoshop CS on your tool bar - go to Window -File Browser - folders - specified folder file - select all -edit -rotate and that is all there is to it

Let me know if it works

Hi Mischa,

I use an older version of Photoshop that doesn't show those menu options. The batch automation function that Heidi explained has been working well, though.

Thanks to all!