[CentOS] Disabling IPv6 in CentOS 4.7

I thought I'd done that standard stuff
  /etc/modprobe.conf:
    alias net-pf-10 off
    alias ipv6 off
  /etc/sysconfig/network:
    NETWORKING_IPV6=no

But on reboot I still see ipv6 entries against the eth devices, ipv6 module
is still loaded, and sit0 tunnel is present.

What needs to be done to disable ipv6?

-- 

rgds
Stephen