Counting Nodes Based on Conditional Statements

I must have a stunted ability to search throughout the archives, because 
once again I can't find anything specific to solve my problem that 
should be common (sigh).
Anyway, I have a stylesheet that displays book titles depending on some 
parameters passed to it. As a result, a dynamic number of books are 
shown. I need to count the number of the book titles that are shown, and 
display the result accordingly. If no book titles are shown at all, I 
need to be able to display message in their absence. Only containing a 
cursory knowledge of variables in XSLT, i'm not yet skilled enough to 
handle this problem on my own. Some help would be great.
An example of the xml document follows:

 <category name="Health &amp; Fitness">
     <book status="Purchased">
       <title>Strength Training Anatomy</title>
       <sub-title>Your Illustrated Guide to Muscles at Work</sub-title>
       <author>Frédéric Delavier</author>
       <isbn>0736041850</isbn>
       <publisher>Human Kinetics Publishers</publisher>
       <date>September, 2001</date>
       <price>13.27</price>
     </book>
   </topic>
   <topic name="Nutrition">
     <book status="Purchased">
       <category>Health &amp; Fitness</category>
       <title>Nutrition For Dummies</title>
       <author>Carol Ann Rinzler</author>
       <isbn>0764540823</isbn>
       <publisher>Wiley Publishing</publisher>
       <date>November, 2003</date>
       <price>15.39</price>
     </book>
     <book status="Purchased">
       <title>Encyclopedia of Sports &amp; Fitness Nutrition</title>
       <author>Liz Applegate</author>
       <isbn>0761513787</isbn>
       <publisher>Prima Publishing</publisher>
       <date>December, 2002</date>
       <price>16.07</price>
     </book>
     <book status="Purchased">
       <title>Nancy Clark's Sports Nutrition Guidebook</title>
       <author>Nancy Clark</author>
       <isbn>073604602X</isbn>
       <publisher>Human Kinetics Publishers</publisher>
       <date>August, 2003</date>
       <price>13.27</price>
     </book>
   </topic>
 </category>

The stylesheet code follows:

 <xsl:param name="category" />
 <xsl:param name="topic" />
 <xsl:param name="status" />

 <xsl:template match="/">
   <div class="line"></div>

   <xsl:for-each select="catalog/category/topic/book">
     <xsl:sort select="title" data-type="text" order="ascending" />
     <xsl:if test="$status = 'All' or ($status = 'Purchased' and 
@status = 'Purchased')">
       <xsl:if test="$category = 'All' or ($category = ../../@name and 
($topic = ../@name or $topic = 'All'))">
         <div><xsl:value-of select="title" /></div>
         <div class="line"></div>
       </xsl:if>
     </xsl:if>
   </xsl:for-each>
 </xsl:template>

</xsl:stylesheet>