Targeting an iframe from dropdown menu

[redpups]

I volunteer to keep a website for a small dog group... I am trying to have a dropdown menu (js) open various links onto an iframe on the main page. The dropdown menu works fine, but always opens the link in a new window (iframe remains blank). I am not a website developer and have no understanding of js or html other than the little bit I've done on this site. Any suggestions would be much appreciated. Here are my files:

http://www.nrsftc.com/main_new.htm (page with menu & iframe)
http://www.nrsftc.com/javascript (js files)
http://www.nrsftc.com/welcome_new.htm (welcome page for initial iframe)
http://www.nrsftc.com/purpose_new.htm (another page to link to iframe)

Thanks much for any advice,
RAF

[Kravvitz]

I suggest you read these articles.
http://apptools.com/rants/jsmenu.php
http://apptools.com/rants/menus.php
I have a much higher opinion of the Suckerfish Menu System than this author, however, he does explain the pitfalls of DHTML menus well.

This page may be old, but it answers your question. (http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/target.html)