Make sure that you have enough storage space on your hard drive before doing this procedure. You may have to export all photos by year to make file management easier on the Windows PC.
Go to 'Events' view and select the event which you want to export. Now you must export the entire event to Windows PC. This will give you the photos in folder which represents the 'Events' in your iPhoto Library. Select 'Original' option in 'Kind' and 'Event Name' option in the 'Subfolder Format' and then click 'Export' button. Click 'File' menu and select 'Export' option. To do so, open 'iPhoto' on your Mac and select all your photos to transfer. You can transfer all your photos from iPhoto to Windows with simple steps. The most important thing is your photos and videos. But if you want change your Mac computer to Windows PC, then you need to transfer you all data from Mac to Windows PC. By default, iPhoto is a photo management program which comes standard on every Mac computer.