FlashPanos

I'm currently using PNG images for a cube panorama. Each face is 1024x1024px and somewhere between 100 and 500KB. This means visitors will be waiting a long time to download them all. Should I use JPG instead? The problem is that the images are raytraced, and therefore have a lot of sharp edges and flat shading, which JPG does not handle well. What other options do I have?

Thanks!

-Mike