If you need to make an interactive slideshow for use on Windows, you need to use something in addition to iPhoto. For whatever reason, iPhoto's QuickTime export feature does not include an option for interactivity. The slideshow shareware apps I've seen use proprietary formats, which are unplayable on Windows.
The solution is to drag your selected images straight from iPhoto into the navigator pane in a new Keynote document. Keynote will automatically create a new slide for each photo. You can then easily rearrange them, and export the slideshow to QuickTime, with the 'interactive slideshow' option selected.
You can also drag from the Finder, but who views their images there?
Mac OS X Hints
http://hints.macworld.com/article.php?story=2004072714521474