One thing to watch out for is not to link to the jQuery library twice, which you've done in the <head> of the page. Try removing the second link to it.
You have a lot of scripts there, so there could be some conflict. What I normally do when using a script is firstly to set it up on a page with nothing else on it except the basic styling of the site. Once it's working in that environment, I move it over to the page it will go on, so that if it doesn't work, I know there's something else going on.
Alos, I don't see the script for that slideshow on your page anyway (unless I'm blind):