[jQuery] xml namespace problems

[Tony]

Sorry if this is a second post, but I do not see my message
here is the xml


<?xml version="1.0" encoding="ISO-8859-1"?>
<lib:catalog xmlns:lib="http://localhost/";>
  <lib:book name="bookext">
    <lib:user name="user">
                <lib:book name="bookint">
                </lib:book>
        </lib:user>
  </lib:book>
</lib:catalog>

1. the expression
$('catalog > book',xml).each(function(){
...
});
does not work in IE6 and FF

2. the expression
$('catalog  book',xml).each(function(){
...
});
Work in FF, but not in IE6

3. the expression
$('lib\\:catalog  lib:\\book',xml).each(function(){
...
});

Work in IE6, but not in FF

Any help on how to solve this problem? or is this bug ?
Thank you in advance
Tony