read id from *.php?id=1 in xsl file??

Hello,

I have an xml file with different pages. The pages have an id. If I want to see page x with id=1, I want to have a parameter with my php file like this default.php?id=1. Then page x with id=1 has to show up on my screen.

i've got hte following xsl file: (part of it)

<table border="0" cellpadding="0" cellspacing="1" width="100%" align="center" height="500" bgcolor="{$body_background}">
<xsl:for-each select="siteinfo/pages/page">
<xsl:choose>
<xsl:when test="id=$id ">
<tr>
<td width="15"><xsl:value-of select="body" disable-output-escaping="yes"/></td>
</tr>
</xsl:when>
</xsl:choose>
</xsl:for-each>
</table>

The $id has to be the id from default.php?id=1

How do I do that??????