Loading Sharepoint Web Services XML List into WPF DataGrid

I'm trying to populate my DataGrid with the returned list from a Sharepoint Web Services, all of the tutorials/guides I've found go about doing this with a XAML file.

This is the code I'm using to pull the XML,

private String GetListNode()
    {
        webService.Lists siteClient = new webService.Lists();
        System.Net.NetworkCredential passCredentials = new System.Net.NetworkCredential("username", "password", "domain");
        siteClient.Credentials = passCredentials;

        XmlNode getNode = siteClient.GetListItems("Tasks", string.Empty, null, null, string.Empty, null, null);

        return getNode.OuterXml;
    }

This returns the pages XML, within this page I'd like to grab these Items,

ows_ID, ows_Client, ows_AssignedTo, ows_LinkTitle, ows_Status, ows_Priority, ows_DueDate

I'd like to make these items Columns for the DataGrid, then having the data populate. All help will be appreciated, thank you in advanced.