Javascript:

<script type="text/javascript" src="http://code.jquery.com/jquery-latest.pack.js"></script>
<script type="text/javascript" src="http://ecn.dev.virtualearth.net/mapcontrol/mapcontrol.ashx?v=7.0"></script>

$(document).ready(function () {
    GetMap();
});

function GetMap() {
    var myMap = new Microsoft.Maps.Map(document.getElementById("mapDiv"), { credentials: "YourKey" });
};

HTML: 

<div id='mapDiv' style="position:absolute; width:800px; height:600px;"></div>