Javascript pop up window code not working

I am using the following code to create a popup from a link:

<a href="javascript:window.open('slideshow_open.php?id=http://www.heartofamericasuperstore.com/images/listing_pics/B8q9xveRtJ_forced_jpg_large.jpg','Slideshow','width=333,height=323')">Test Link</a>

For some reason it opens the popup window as well as taking the current page to a blank page w/ the word [object Window] on it. Does anyone have an idea as to how to keep this from happening and still be calling the javascript in the href attribute? (I am eventually going to be calling it from a getURL() in flash…