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The XSL file gets the element local names and uses them for the header row in the Excel spreadsheet. This way you don't have to have the column names in the XSL. And you can resuse the XSL with any XML file that is in the proper format. This generic XSL will work if you have one column or many columns. In addition, the XSL gets the second level element local name and uses it for the worksheet name.

<xsl:stylesheet version="1.0"
    xmlns="urn:schemas-microsoft-com:office:spreadsheet"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
 xmlns:msxsl="urn:schemas-microsoft-com:xslt"
 xmlns:user="urn:my-scripts"
 xmlns:o="urn:schemas-microsoft-com:office:office"
 xmlns:x="urn:schemas-microsoft-com:office:excel"
 xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" > 
 
<xsl:template match="/">
  <Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
    xmlns:o="urn:schemas-microsoft-com:office:office"
    xmlns:x="urn:schemas-microsoft-com:office:excel"
    xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
    xmlns:html="http://www.w3.org/TR/REC-html40">
    <xsl:apply-templates/>
  </Workbook>
</xsl:template>


<xsl:template match="/*">
  <Worksheet>
  <xsl:attribute name="ss:Name">
  <xsl:value-of select="local-name(/*/*)"/>
  </xsl:attribute>
    <Table x:FullColumns="1" x:FullRows="1">
      <Row>
        <xsl:for-each select="*[position() = 1]/*">
          <Cell><Data ss:Type="String">
          <xsl:value-of select="local-name()"/>
          </Data></Cell>
        </xsl:for-each>
      </Row>
      <xsl:apply-templates/>
    </Table>
  </Worksheet>
</xsl:template>


<xsl:template match="/*/*">
  <Row>
    <xsl:apply-templates/>
  </Row>
</xsl:template>


<xsl:template match="/*/*/*">
  <Cell><Data ss:Type="String">
    <xsl:value-of select="."/>
  </Data></Cell>
</xsl:template>


</xsl:stylesheet>