Hi Donald,
Ah, you've encountered the bugaboo that bedevils so many of us.
IIRC, KMN gallery is kinda optimized for less than 1,000 pixels; regardless, the bigger the image, the larger the file size. Here is a trick I learned that reduced the file size per image from a MB to a couple of hundred KBs. A lot of image file size is due to formatting by the camera software. I found that if you open the image in another program (I used good ol' Windows Paint for a long time.) and then simple resaved it, that stripped a lot of the previous e-gunk out and dramatically reduced file size.
My now use Windows Live Photo Gallery; it allows me to snare all the images in a folder and resize all as a batch. There are many other photo programs out there that you can use. Or download Paint.Net - lots of editors here at KMN use it.
Hope this helps. If you need more, there are some tutorials in the forums about reworking you images.