Is there a plugin like this? (a better password protection for a page)

Hi

is there a plugin that will let me do this:

a page is accessible to everyone, it has some content on it and beneath a form where a password can be accessed. Once the correct password is entered all of the content changes into something else. So, old content is displayed before the pass is entered, and once the password is entered old content gets removed and new content gets displayed. How do I do this?

Also, is there a plugin so that password can be case-insensitive? If the pass is abcdef and a visitor enters ABCDEF it should also grant him access to password protected content.

Thanks for the help!