with your internet connection running before you chroot copy the file resolv.conf to your new system.
cp -f /etc/resolv.conf /mnt/hda*/source/KNOPPIX/etc/resolv.config
Like this your DNS Server in the new system is ok. Now chroot:
chroot /mnt/hda*/source/KNOPPIX
Then mount proc: mount -t proc /proc proc
ping google.com should work now. If not try ping 216.239.59.99 if this
works your DNS sever address is wrong.
unno