This is much easier and more robust if you
use LinkButtons, as Rion suggested.
You can add an attribute to the LinkButton
in your Page_Load or some other initialization
method:
LinkButton.Attributes.Add("onclick", "javascript:window.open('" + "continents.aspx" + "'," +"'linkwindow', 'width=405,height=465')");
and this enables you to use different window sizes, if you choose, or
even add parameters to the QueryString that have come from
a database or other source.