If your just replacing one disk for another, e.g same space you could use dd.
dd will copy the disk block by block including the boot sector (boot loader) etc.
Simply install new harddrive into the exsisting system.
use dd to copy the entire disk.
Assuming you want to replace a disk of the same size this would be the least hassle and on the same machine. If your changing disks to increase space then this is just one option or to clone a disk to put in a another machine.
I can't help you with what the device names are on suse (I use FC (redhat)) myself but dd if=(input disk) of=(new disk) bs=512.
Remember you need the entire disk not just the partition.
Also do it from single user mode and ensure you havw fsck'd all your filessystems as you will copy over any problems otherwise.
Hope that helps a bit.