AFAIK - XAMMP defaults to SSI working (and to make sure I just tested with a clean install)
the "It Works" index.html page now says:It works!
So - First, I guess we should check if SSI's are enabled
go to the XAMPP page http://localhost/xampp
and click Status - does SSI show as Activated?
if not check this line in \xampp\apache\conf\httpd.conf to make sure its not commented out.
LoadModule include_module modules/mod_include.so
Also check this section to make sure Includes is there.
Options Indexes FollowSymLinks Includes ExecCGI
Just another thought? do you have either a .htacess file in /htdocs OR are you using a vhost?
As for your seconf question, the Xbit hack probably won't work on Windows, so "I don't know!"http://www.zytrax.com/tech/web/ssi.htm#overview