var myvar;

function myFunction(myparam){
myvar = "top=18,left=24,resizable=yes";
myvar = myvar + ",width=" + (screen.width-75)
myvar = myvar + ",height=" + (screen.height-140);

if (myparam == 'contact'){
myvar = myvar + ",toolbar=no"
myvar = myvar + ",location=no"
myvar = myvar + ",directories=no"
myvar = myvar + ",status=yes"
myvar = myvar + ",scrollbars=yes"
myvar = myvar + ",menubar=no"
}
window.open("pages/contact.htm", "mypage", myvar);
}