Netscape exclusion

I have created the following code to hide/show a section on a form. What I am looking for is a little assistance to exclude this from netscape 4.xxx and possible other browsers. Right now I mostly concerned with 4.xxx. About 90% of the features in the site still work well with Netscape 4.xx so I would like to keep this that way if possible.

<script language="JavaScript" type="text/JavaScript">

</script>

Thank you in advance!!!!