Using sum to Produce a total from combined documents

I need to get a total using a calculation.

I have two files, one containing current stock information, and the second
contains short stock information, and the number of shares owned.

I need to take the last-sale-price, multiply it by the @shares (in config)
and produce a total.  I have this completed, and it wasn't a problem.

I need to create a total for this column though - it should produce a total
value of the portfolio. (adding up all of the values discussed in the
last paragraph.)  This would be inserted where the phrase "TOTAL HERE" is below.

I'd greatly appreciate a solution for this.  I'm quite sure the solution is simple,
but it's eluding me.

XML and XSLT files are below.

--
Eric Vitiello [Perceive Designs]
<http://www.perceive.net>
Got Geek? <http://www.cafepress.com/got_geek>


(I've removed some data for ease of reading and explanation)

stock.xml
-------------------------------
<nasdaqamex-dot-com>
	<equity-quote symbol="DIS">
		<issue-name>DISNEY CO WALT HLDG CO</issue-name>
		<last-sale-price>18.27</last-sale-price>
	</equity-quote>
	<equity-quote symbol="SYQTQ">
		<issue-name>Syquest</issue-name>
		<last-sale-price>.02</last-sale-price>
	</equity-quote>
</nasdaqamex-dot-com>
-------------------------------

config.xml
-------------------------------
<config>
	<stocks>
		<stock symbol="DIS" type="stock" shares="40"/>
		<stock symbol="SYQTQ" type="stock" shares="200"/>
	</stocks>
</config>
-------------------------------


my XSL, which is being applied to stock.xml:
-------------------------------
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output method="html" indent="yes" />
	<xsl:variable name="config" select="document('config.xml')/config" />

	<xsl:template match="nasdaqamex-dot-com">
		<div id="stocks">
			<table cellspacing="0" cellpadding="1" width="100%">
				<tr>
					<th>name</th>
					<th>symbol</th>
					<th>last</th>
					<th>value</th>
				</tr>
				<xsl:apply-templates select="index-quote" />
				<xsl:apply-templates select="equity-quote" />
				<tr><td align="right" colspan="7">Total Value</td><td>TOTAL HERE</td></tr>
			</table>
		</div>
	</xsl:template>
	
	<xsl:template match="equity-quote">
		<tr>
			<xsl:attribute name="class">
				<xsl:choose>
					<xsl:when test="number(net-change-price) &lt; 0">priceDown</xsl:when>
					<xsl:otherwise>priceUp</xsl:otherwise>
				</xsl:choose>
			</xsl:attribute>
			<xsl:variable name="currentSymbol" select="@symbol"/>
			<td><xsl:value-of select="issue-name"/></td>
			<td><xsl:value-of select="@symbol" /></td>
			<td><xsl:value-of select="last-sale-price"/></td>
			<td><xsl:value-of select="format-number(($config/stocks/stock[@symbol=$currentSymbol]/@shares * last-sale-price),'$###,##0.00;($###,##0.00)')"/></td>
		</tr>
	</xsl:template>
</xsl:stylesheet>
-------------------------------


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