Keeping any given image below 50k would be a good goal, I think.
If you're willing to do just a slight amount of hand coding, you could easily use thumbnails that open a pop-up window with a larger picture in it. You could use your program to add/arrange thumbnails (I often aim for around 100px wide), use your program to make them links, and then just change the link text to a tiny bit of code I could supply for you.
Anyway, it's not a big deal, and your site's pretty nice the way it is. But let me know.
Nate