grey out submit button until form filled out

[ramses3]

I have the following form:\[code\] <form action="http://www.tahara.es/contact/subscribe.php" method="post" id="subscribe" name="subscribe"> <input type="hidden" name="action" value="http://stackoverflow.com/questions/14614761/subscribe"> <label>NAME:</label> <input type="text" name="name" class="Textbox" id="sub_first_name"> <label>EMAIL:</label> <input type="text" name="email" class="Textbox" id="sub_email"> <input type="submit" name="button" id="button" value="http://stackoverflow.com/questions/14614761/Subscribe" />\[/code\]I would like to grey out the \[code\]submit\[/code\] button until both fields in the form have been filled out. I guess jquery would do the trick?How can I do this, and where should I place the script?