I would get the first pic, because its cheaper, but if you want MP4 that looks like a iPod nano then go with the second pic, it doesn't really matter which one you get, because they both have the same firmware and screens are the same size, but if I where you just get the first pic.
*edit*
or maybe go with this, bigger screen, aroudn the same price range, and looks nicer than the first pic you have here.
http://www.deremate.cl/accdb/viewitem.asp?idi=13828149
or this one
http://www.deremate.cl/accdb/viewitem.asp?idi=13186859