I already gave you code that will allow you to open and close divs. You can do this basically by setting the css "display" value to "none" or "block".
Now if you want this selection to be remembered for future visits you'll need to have them log in, or you will need to store this in a cookie.
, Moo Tools
, or YUI
What you want to accomplish can be done through any of those libraries and if you are going this direction you might want to start playing with them to learn more about dynamic html.