That's the kernel you're using. But what distribution (and what version of distribution)? I'm guessing perhaps a RHEL, Fedora, or CentOS installation?

Update 1: Looks like that kernel was distributed with CentOS 4.6.

Update 2: Both libxml2 and XML::LibXML are available from the CentOS 4.6 archives. These are much older versions than current of course, since 4.6 is pretty darn old. These are the packages, install using a package manager.

• libxml2-2.6.16-10.i386.rpm
• libxml2-devel-2.6.16-10.i386.rpm
• perl-XML-LibXML-1.58-1.i386.rpm

Perhaps it's time to upgrade that OS?

Ok, enough sysadmin; back to perl!