C# - Asp:CreateUserWizard Redirecting After Complete?

I have an asp registration page using a custom asp:CreateUserWizard.

Once the registration is completed successfully (RegisterUser_CreatedUser for example) I want to redirect the user to another page, be it a welcome screen, etc... (using Response.Redirect(URL); I guess), but I also want to, some how, popup a new window with the login page.

Is it possible to popup a screen from an external url using this method, or is there another way I should go about it?

I did try creating a custom button which calls this js function for registration:

function redirectAfterRegister() {
Page_ClientValidate();
if (Page_IsValid) {
window.open('/Account/Login.aspx?UserCreated=True');
$('#CreateUserButton').click();
}
return false;
}

This popup works because its called off a click, but the problem with this is the popup is always called even if the creation of the user was unsuccessful - which is wrong.