how to open a page and force an iframe load?

Starx

Include the following js script on the main page and you are done

function loadframe(){
  var i = document.getElementById("iframeID");
  i.src = "path/to/file";
};

// Check for browser support of event handling capability
if (window.addEventListener)
    window.addEventListener("load", loadIframe, false);
else if (window.attachEvent)
    window.attachEvent("onload", loadIframe);
else window.onload = loadIframe;