Performance best practices:
If you're using a library such as jquery or prototype, I recommend instead of hosting the file or files yourself, reference the one google has hosted. You can find the urls for the minified and uncompressed files here: http://code.google.com/apis/ajaxlibs/documentation/The reason to use the library this way is that it helps with load times. This is achieved by the fact that many other sites utilize the documents hosted there, and therefore visitors of your site will benefit from having the resource cached already. Another thing is that it's google, and you can therefore count on it being up all the time. Be sure to use the minified files. They are compressed, and therefore load a bit faster.