First, does anyone know of a good free program to create a flash gallery?

I am currently using SimpleViewer and I have a question about the size of the
photos. All the pictures are different sizes and SimpleViewer allows me to set
a maxium height and width. (maxImageWidth)

For some reason, it stretches some photos and it doesn't keep the size of the
photos (I have it set at 480 for both height and width). I am looking for
gallery that will allow me to 'auto' set the height and width so that the size
of the photos won't be stretched out and will appear as I have uploaded them.