How can I make submit buttons inactive unless checkbox is checked?

I am working on a form to gather some information about the visitors. However, I do not want them to be able to send the form unless a certain checkbox is checked. I know it would be easy to conduct a form validation on the checkbox, but I would like to know if it is possible to make the two (I want to know wheter there is a difference between my own submit buttons or the default buttons) submit buttons look “faded” or at least not clickable until the checking is complete. I guess I need some ‘onclick’ or ‘onchange’ code to solve the problem, but do not know what that function should look like.

Hope you can help, here is the form code.

<form name=”form1″ method=”post” action=”someURL.asp”>
<p>
<input type=”checkbox” name=”check1″ value=”1″>
If checkbox is not checked the two submit buttons will not work. </p>

<p>
<Input type=”submit” name=”Submit” value=”Send”>
</p>
<p>
<input name=”send” type=”image” id=”send” src=”Images/send.gif” alt=”Send” border=”1″>
</p>
</form>

Also in #JavaScript _↴