I have copied and pasted your code and it runs fine for me in IE, Firefox and Opera.
Are you sure you have the jquery-1.3.1.min.js as pointed to in your head, or do you have the normal jquery-1.3.1.js?
That's all I can think of really
I think I figured out the problem. I have that intellsense file and it is so picky. If you have the jquery script before the intellsense file at run time I don't know what happen it does not work. If you move the file up so the intellisense file is above the jquery script it works.