Selectively convert subordinate elements to text

Hi,
 
I have a fragment something like this:
 
 
        <widget>This <B>is</B> some <SUP>text</SUP> that I want to convert
<HIDDEN>don't convert this</HIDDEN> to text</widget>
 
 
What I want to end up with is this:
 
        This is some text that I want to convert to text
 
I have tried <xsl:value-of select="."/> but of course that gives me:
 
        This is some text that I want to convert don't convert this to text
 
Can anyone suggest a way that I can convert the fragment to text while
simultaneously dropping the <HIDDEN> element?
 
Thanks

D.