<a href="javascript:void()" onclick="window.open('myPage.aspx');">Open New Window</a>
Ought to do it. As others have mentioned, the # is trying to go to a non-existent anchor, which will cause the browser to scroll to the top. You don't want to remove the href attribute, because some browsers don't treat <a>
tags without href attributes as links for styling purposes, and you would have to define additional CSS rules to ge thte link to look like other links on your site.
Also, why have an href attribute and then try to block the event by always returning false from your handler. In my opinion, this way is cleaner than the others proposed here.