Is there a way to open to url's with Javascript? Basically what i am trying to do is have a banner on my page and when users click it it will open the sponsor page for the banner but it will also open up the next page on my site. i am sure i have seen it doen but i cannot find anything on this. Thanks.

<a href="nextpage.html" onclick="window.open('sponsorpage.html')">
   <img src="banner.gif" border="0" />
</a>

Thanks