I can't get these pages to load on my dial-up very well, even though it does have a dial-up option, but I heard about this from one of my homeschooling lists:
http://www.bl.uk/onlinegallery/ttp/ttpbooks.html
I was told that there is even an option on the Leonardo Da Vinci pages to flip his reversed text so that you can see it right. It looks very cool, just wish I could get them to load faster!