Exporting your photos out of iPhoto is easy. To keep things organized, I like to create a Photo Export folder on my desktop so that everything ends up in the same place.
Click on Last Import in the Source List. Then go to the Edit menu and choose Select All. All your photos should be highlighted with a yellow border.
Go to the File menu and select Export... For photos, you want to mirror these settings. Be sure the Include options are checked. They ensure that your metadata is included in your photos.
You can also export groups of photos as a QuickTime movie. Check include music if you want the default music to be included. Generally it's best to leave it unchecked.