Javascript in Header?

I’m am amateur web designer helping a friend with a site and this is my first time using WordPress. The main site is made in HTML and the menu buttons are javascript. I’m trying to add these same buttons to the blog in header.php in order to make them appear over the banner (twenty-ten theme with modified CSS), but the script keeps breaking everything and the blog won’t appear at all. My knowledge of PHP is pretty limited. Could anyone tell me where to add the script to make those buttons appear and work on the blog as well as the main site?

The site and blog are located here:
Chaotic Exotics
Chaotic Exotics Blog

The script I’m using for the buttons is as follows:

<SCRIPT LANGUAGE="JavaScript">

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin

image1 = new Image();
image1.src = "images/homeover.gif";

image2 = new Image();
image2.src = "images/zooover.gif";

image3 = new Image();
image3.src = "images/blogover.gif";

image4 = new Image();
image4.src = "images/blogover.gif";

image5 = new Image();
image5.src = "images/guestover.gif";

image6 = new Image();
image6.src = "images/bioover.gif";

image7 = new Image();
image7.src = "images/downloadsover.gif";

image8 = new Image();
image8.src = "images/contactover.gif";

// End -->
</script>

With this in the HTML:

<a href="home.html" onmouseover="image1.src='images/homeover.gif';"onmouseout="image1.src='images/home.gif';"><img name="image1" src="images/home.gif" width=94 height=100 border=0></a>
<a href="zoo.html" onmouseover="image2.src='images/zooover.gif';"onmouseout="image2.src='images/zoo.gif';"><img name="image2" src="images/zoo.gif" width=149 height=100 border=0 /></a>
<a href="gallery.html" onmouseover="image3.src='images/galleryover.gif';"onmouseout="image3.src='images/gallery.gif';"><img name="image3" src="images/gallery.gif" width=120 height=100 border=0></a>
<a href="blog/?p=50" onmouseover="image4.src='images/blogover.gif';"onmouseout="image4.src='images/blog.gif';"><img name="image4" src="images/blog.gif" width=90 height=100 border=0></a><a href="bio.html" onmouseover="image6.src='images/bioover.gif';"onmouseout="image6.src='images/bio.gif';"><img name="image6" src="images/bio.gif" width=93 height=100 border=0></a>
<a href="downloads.html" onmouseover="image7.src='images/downloadsover.gif';"onmouseout="image7.src='images/downloads.gif';"><img name="image7" src="images/downloads.gif" width=159 height=100 border=0></a><a href="contact.html" onmouseover="image8.src='images/contactover.gif';"onmouseout="image8.src='images/contact.gif';"><img name="image8" src="images/contact.gif" width=111 height=100 border=0 /></a>

Thanks in advance.