This information is, at least for the case of Word, provided by the MS Word Object Model. For the other cases, I don't know, especially for the .pdf files, as I don't know whether Acrobat Reader provides an OLE interface to the application and its document. The best way in my opinion is still to print the documents to a printer and then count the pages of the output. That printer does not necessarily need to be a real paper printer, but for example a .pdf printer, if you know how to get the number of pages in a PDF file.

For printing any document under Windows, take a look at the shell commands provided in the registry of Explorer and/or at the facilities for automating (Office) applications provided by Win32::OLE. For getting the count of pages out of a PDF, I would look at the (various) PDF modules that CPAN provides.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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