Photoshop CS2 is Adobe's advanced photo editor, mainly for professionals. Photoshop Elements 4.0 would be enough for most of the basic photo editing and it's a bit easier to use. Elements has the photo album and organizing feature, whereas CS2 doesn't. Since it is more for the consumer, it's also quite cheaper if you were to purchase it. Here's the link to Elements 4.0:
http://www.adobe.com/products/photoshopelwin/main.html
Link to Photoshop CS2:
http://www.adobe.com/products/photoshop/main.html