Shoutbox

Ok I have this javascript code:

code:

---

function getElem(id) {
    var divid = document.getElementById(id);
    return divid;
}

function msnAddShow() {
    var form = getElem('hostsu');
    var tblrow = getElem('msnadd');
    var msnAdd = null;
    for (i=0; i<form.msn.length; i++) {
        if (form.msn[i].checked) {
            msnAdd = form.msn[i].value;
        }
    }
    if (msnAdd == "yes") {
        tblrow.style.display = "table-row";
    }
    else {
        tblrow.style.display = "none";
    }
}

---

Problem is that it doesn't work in IE. What it's meant to do is detect if someone has selected 'yes' to the radio button 'do you have MSN Messenger?' and, if they have, display a text box beneath it for them to enter their MSN address. Live code is at: http://www.teaspoondiner.net/hosting.php?act=signup

It works in all browser BUT IE... is there something I can change for it to work in IE as well as the other browsers?