Hi,
also ich hab noch 2 Tipps:

1. <script language="JavaScript" type="text/javascript">
2. <a href="#" onclick="na_open_window('...usw.

bei mir siehts so aus:

<script language="JavaScript" type="text/javascript">
<!--
function na_open_window(url, name,  left, top, width, height, toolbar, menubar, statusbar, scrollbar, resizable)
{
[...]

<a href="#" onclick="na_open_window('bilder_studio1.html', 'bilderstudio1', 0, 0, 640, 480, 0, 0, 0, 0, 0)" target="_self">[...]

...und klappt...

Gruß,
Manu