I have WordML data like this...
<w:r>
   <w:rPr>
	   <w:i>
         <w:u w:val="single"/>
         <w:b/>
    </w:rPr>
     <w:t>I have bold and italics and underscore
</w:t>
</w:r>

starting from this xml:
<w:r xmlns:w="specify-the-namespace-here">
	<w:rPr>
		<w:i/>
		<w:u w:val="single"/>
		<w:b/>
	</w:rPr>
	<w:t>I have bold and italics and underscore
	</w:t>
</w:r>

You'll get this output:
<i>
	<u>
		<b>I have bold and italics and underscore
	</b>
	</u>
</i>

<xsl:template match="w:r ">
	<xsl:apply-templates select="(w:rPr|w:t)[1]"/>
</xsl:template>

<xsl:template match="w:rPr">
	<xsl:apply-templates select="*[1]"/>
</xsl:template>

<xsl:template match="w:rPr/*">
	<xsl:element name="{local-name()}">
		<xsl:apply-templates select="(following-sibling::*|../../w:t)[1]"/>
	</xsl:element>
</xsl:template>

I hope this is useful
I don't know wordML, so I can't guarantee this solution works in all cases.

regards,
--
Joris Gillis (http://www.ticalc.org/cgi-bin/acct-view.cgi?userid=38041)
Veni, vidi, wiki (http://www.wikipedia.org)