get something professional, ie; http://flashden.net/files/29641/index.html ( http://flashden.net/item/advanced-xml-image-gallery-/4746 ) or http://flashden.net/files/50320/index.html ( http://flashden.net/item/professional-xml-gallery/19064 )
go with a free image script and get some to install it for you if u dont know how to work with flash or coding
I think i can suggest you to have a look of a gallery, impawards.com which showcases beautiful posters of Hollywood Movies and the designing of that site is really gr8.