Hmmm, I do see something strange. Your root is /dev/hda3 and your boot is /dev/hda1. That's fine, I have an similer setup. But Shoulden't grub.conf look like :
kernel (hd0,0)/kernel-2.4.20-gentoo-r9 root=/dev/hda3
cos "/boot/<bla>" could be the path once you have actually booted and mounted the boot partition. If you suply /dev/hda1 as root to grub, you should leave "/boot" out.