xslt, passing attributes through a url

What I am trying to do is pass variables along with a url like this:

<a href="some_where.php?some_var=howdy">some text</a>

Easy enough but I can't get it to work with xslt. Here is clip of the xslt file:

<xsl:template match="previous">
<xsl:choose>
<xsl:when test="@offset=''"><xsl:value-of select="."/></xsl:when>
<xsl: otherwise><a href="search.php?offset={@offset}&query={@query}"><xsl:value-of select="."/></a></xsl: otherwise>
</xsl:choose>
</xsl:template>

The data that needs to be passed is contained in the 'previous' nodes attributes. I tried including them using {@attribute_name} but no go. This is the error I get:

Warning: Sablotron error on line 125: XML parser error 4: not well-formed (invalid token) in /Users/mikey/Sites/hawaii_rentals_new/search.php on line 201
An error ocurred: XML parser error 4: not well-formed (invalid token)(error code 2)

How can I grab those attribute and pass them along with that url? I think it's breaking on the '&' symbol in the url but I don't know how to get around that.

Mahalo for any help

Figured it out. It was breaking on the '&' sign. So I replaced it with '& amp;' and now I can happily pass vars through the url like this:

<xsl:template match="pages">
<xsl:for-each select="page">
<xsl:choose>
<xsl:when test="@offset='' "><xsl:value-of select="."/></xsl:when>
<xsl: otherwise><a href="search.php?offset={@offset}&query={@query}"><xsl:value-of select="."/></a></xsl: otherwise>
</xsl:choose>
</xsl:for-each>
</xsl:template>