using DomXML and getting the attribute tag

Using PHP 4.4.8 and DomXML , how can I go about reading the following
XML content? I don't need help reading the file, I need help obtaining
the "value" attribute of each element within the topmost element.

<?xml version="1.0" encoding="UTF-8"?>
<CustomStyle>
<StyleFormat.foreground value = "0xFFFFFF" />
<StyleFormat.background value = "0xFFFFFF" />
<TabTextColor value = "0xFFFFFF" />
</CustomStyle>

/** Code Start **/
$noderoot = $dom->document_element();
$childnodes = $noderoot->child_nodes();

// build the array and output the elements
foreach ($childnodes as $value) {
echo $value->tagname . " : " . $value->get_content() . " : ".
$value->get_attribute['value'] ."<br>";
$nodeArray[$value->tagname] = $value->get_content();
}
/** Code Finish **/