Hi saralh,
To view more EXIF info than iPhoto will show for an image, download Simple EXIF Viewer for Mac OS X. Put it in your applications folder and then open the app. When the app is in the dock, click and hold on it and scroll to "keep in dock".
You can now drag an image from the iPhoto Library viewing window on top of the EXIF viewer. The viewer window will open and give you the EXIF info for the image.
Simple EXIF Viewer for Mac OS X