browser_name = navigator.appName;
browser_version = parseFloat(navigator.appVersion);

if (browser_name == "Netscape" && browser_version >= 3.0) { roll = 'true'; }
else if (browser_name == "Microsoft Internet Explorer" && browser_version >= 3.0) { roll = 'true'; }
else { roll = 'false'; } 

function OpenWindow(address,WindowWidth,WindowHeight)
{
 WindowWidth=WindowWidth+21;
 WindowHeight=WindowHeight+24;
  if (roll == 'true')
  {
    WindowPosition='';
      if (browser_version >=4)
      {
        WindowLeft=Math.round((screen.width-WindowWidth)/2);
        WindowTop=Math.round((screen.height-WindowHeight)/2);
      }
      if (browser_name == "Netscape")  {  WindowPosition='screenX='+WindowLeft+',screenY='+WindowTop; }
      if (browser_name == "Microsoft Internet Explorer") { WindowPosition='left='+WindowLeft+',top='+WindowTop; }

    newWindow=window.open(address, null, WindowPosition+
    				',width='+WindowWidth+
                             	',height='+WindowHeight+
                              	',toolbar=0,scrollbars=0,resizable=0');
    newWindow.focus();
  }
}