Well, but your second ifconfig output shows clearly, that there is
an IPv6 link-local address assigned to eth0, which happens only if
the IPv6 kernel module gets loaded. So in fact, your box _was_ IPv6
enabled in both cases.
Oops. Nope, that was just a bad cut and paste job on my part. The
inet6 addresses definitely don't show up when I do the ifconfig with
the ipv6 "disabled". My mistake. Will try it again tonight, correctly.
I think it looks the same, except no inet6 addr. Sorry for the
misleading info!