Generally speaking, if a script doesn't run in a later version, you can put it in a subfolder withteh correct version number as the name and it will work. For CS3 that would be "Version 5.0 Scripts" without the quotes.
That said, if you have Acrobat pro, it's probably easier to use the extract pages command...
Thank you. I'll give the CS3 script a try. Unfortunately it has to be separate InDesign documents because that's the way our seedpack printer wants them.
As I said, if you export a multipage PDF, you can use the extract pages command in Acrobat Pro to break it into single page files....