from your grub.conf file
appears fishy, are you sure this is the exact location of the boot partition?
kernel /vmlinuz ro root=/dev/hda3
again, are you sure /dev/hda3 is the correct location of the kernel image? not /dev/hdb ?
as in, is this the older harddrive still connected? that is referred to as hda
Prim master is /dev/hda
i think the problem lies in those lines