Opening New Window

I'm sure it's easy, but...

[m2c1r]

How do I get this link to open in a new window?

"<script language='javascript'> document.location='".$siteurl."/folder/index.php';</script>"

Thanks,

Matt

[Trace]

<script type='text/javascript'>window.open('".$siteurl."/folder/index.php');</script>