Why don't animated pcs. play in Photo Gallery

Vista Home prem. 32 bit
In WinXP the animated pictures would play in what XP called Windows Picture and Fax viewer. Now Vista has what it calls Windows Photo Gallery but the animated pictures don't move, i.e. play! It displays them as a still photo. I would think its for some safety reason? lol....... If anybody knows anything about this please reply, thank you. ...Rob