Just boot with your current installation (small hdd) and attached second new disk (big hdd).
tar cvf linux.tar / - create linux.tar from root [/]
mount /your/new_drive /mnt/something (after file system create)
cd /mnt/something - change dir where is mounted your new drive
tar xvf path_to/linux.tar - extract tar file with your current distro under new hdd
OK now you have your current installation to your new drive !
now type chroot /mnt/something - this will change your root to destination that you used for untar your distro
lilo -v - this will install lilo (if you use lilo) to your new hdd
power off and boot from your new drive.
another way is to tar and untar trough pipe without first tar and after this untar (if you do not space)