Opening Document in native application with IE?

Hi, I'm using DWMX 2004 with PHP and I allow users of the system to attached
documents. Now, when someone wants to view this attachment by clicking on it
in IE 6.x, it spawns a new browser window with the document in it. However, I
noticed that Netscape 7.1 opens the document in it's native application as
well as en empty browser window. Thus, is there a way to force IE to open the
document in its native application instead of using 'target='_blank'?

Thanks in advance,

-Conrad