Hi Paul,

It's hard to know until you've tried it, but you need to convert an XML variable into a node-set to be able to query it with XPath - it's easy to do. Here's a full sample.

<?xml version="1.0" encoding="utf-8" ?>
<xsl:stylesheet
    version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:umb="urn:umbraco.library"
    xmlns:make="urn:schemas-microsoft-com:xslt"
    exclude-result-prefixes="umb make"
>

    <xsl:output method="xml" indent="yes" omit-xml-declaration="yes" />

    <xsl:param name="currentPage" />

    <xsl:variable name="CategoriesProxy">
        <Category Item="A" />
        <Category Item="B" />
        <Category Item="C" />
        <Category Item="D" />
        <Category Item="E" />
    </xsl:variable>
    <xsl:variable name="categories" select="make:node-set($categoriesProxy)" />

    <xsl:template match="/">
        <xsl:for-each select="$categories/Category">
            <tr class="odd">
                <td align="left" style="height:48px;">
                    <xsl:value-of select="umbraco.library:ReplaceLineBreaks($currentPage/*[name() = concat('Dept', current()/@Item)])" disable-output-escaping="yes" />
                </td>
                ...
            </tr>
        </xsl:for-each>       
    </xsl:template>

</xsl:stylesheet>

Note that I've changed the reference to @alias - if you're actually using the old XML schema you can change it back.

/Chriztian