In summary, if you were switching library, I would switch to jQuery. Prototype is probably the worst library in existance, so anything would be better. The ideal would be a custom built solution tailored to the site. If you are going to seriously rewrite it to jQuery, you might as well go the whole way and write a nice lean clean script. However, this might be impractical due to your knowledge (only you know that), and if it is, then you should probably go to jQuery.