Getting Longitude and Latitude using JavaScript for Microsoft Dynamics CRM 4.0

I've developed this script for my customer - it gets longitude and latitude using webservise http://rpc.geocoder.us/ based on address. The Code:

RefreshCoords = function()
{
    var address = '';
    if (crmForm.all.address1_line1.DataValue != null)
        address = crmForm.all.address1_line1.DataValue;

    if (crmForm.all.address1_line2.DataValue != null)
        address += (address == '' ? '' : ', ') + crmForm.all.address1_line2.DataValue;

    if (crmForm.all.address1_city.DataValue != null)
        address += (address == '' ? '' : ', ') + crmForm.all.address1_city.DataValue;

    if (crmForm.all.address1_stateorprovince.DataValue != null)
        address += (address == '' ? '' : ', ') + crmForm.all.address1_stateorprovince.DataValue;

    if (crmForm.all.address1_postalcode.DataValue != null)
        address += (address == '' ? '' : ', ') + crmForm.all.address1_postalcode.DataValue;

    var xHReq = new ActiveXObject("Msxml2.XMLHTTP");
    xHReq.Open("GET", "http://rpc.geocoder.us/service/rest?address=" + address, false);
    xHReq.Send(null);

    if (xHReq.statusText == "OK")
    {
        var oXmlDoc = new ActiveXObject("Microsoft.XMLDOM");
        oXmlDoc.async = false;
        oXmlDoc.loadXML(xHReq.responseText);

        try
        {
            var long = parseFloat(oXmlDoc.selectSingleNode("//rdf:RDF/geo:Point/geo:long").text);
            var lat = parseFloat(oXmlDoc.selectSingleNode("//rdf:RDF/geo:Point/geo:lat").text);

            crmForm.all.address1_latitude.DataValue = lat;
            crmForm.all.address1_longitude.DataValue = long;
        }
        catch(e){}
    }
}

I've added this function to OnLoad event handler and pasted call of this functions to fields Address1 - Line 1, Address1 - Line 2, Address 1 - City, Address 1 - State/Province, Address1 - PostalCode.

But as I know this function will work only for users from USA and UK.