Frontpage has a feature that automatically creates thumbnails to your specified size.
The method above will work but your page will load extremely slow due to file sizes and processing power to resize it and the image may look a little off depending on the browser.
I don't use frontpage but I use image editing software to batch convert all the images. I insert the thumbnail size and link it to the full size image. (the browser will open a new page when opening a photo alone)