Newbie..Need Help with Form Calculations

Hello,
I am helping someone do a page for thier site. The want it similar to this one with the calculations: http://www.security-nss.com/DesignDetail.html.
If you know how they are doing this without anything showing up on the page, please let me know.
I did something similar to this in school but it calculated the total on the page. I havent really used javascript in a while so it looks fairly easy but my brain is dusty.
Please help!:confused:

I'm not sure what I'm supposed to see on that site. I entered a few numbers and nothing happened.

Look at this post though. It has an example of what it might be you are looking for

http://www.codingforums.com/showthread.php?t=102452#post512279

david_kw