Ok, you're getting there. The fact that you get a grub shell indicates that /dev/hda3 is the boot partition of your linux distro.

Try the following in the grub shell, and see if anything boots:

root (hd0,4)
kernel /bzImage root=/dev/hda4
boot


If that fails, also try;

kernel vmlinuz root=/dev/hda4

or

kernel vmlinux root=/dev/hda4