<p>I have a few links that should all open in the same window or tab.
To accomplish this I've given the window a name like in this example code:</p>

<pre><code>&lt;a href="#" onClick='window.open("http://somesite.com", "mywindow", "");'&gt;link 1&lt;/a&gt;
&lt;a href="#" onClick='window.open("http://someothersite.com", "mywindow", "");'&gt;link 2&lt;/a&gt;
</code></pre>

<p>This works OK in internet explorer, but firefox always opens a new tab/window.
Any ideas? </p>

The window.open() function in Javascript is specifically designed to open a new window, please see:
w3schools documentation
. It actually sounds like IE is handling things in a non-standard way (which is hardly surprising).
If you want to relocate the existing location to a new page using Javascript, you should look at the
location.replace()
function.
Generally speaking I would recommend that you develop for Firefox and then fix for IE. Not only does Firefox offer better development tools but its implementation of W3C standards tends to be more correct.