If I understand you correctly, you want to move your data/partitions from the old hard drive to a new hard drive. If this is the case and you're buying a retail hard drive, they usually come with software to handle this (well, at least Maxtor does).
If you don't have the software you can read this for some assistance.
http://www.gnu.org/software/parted/m...no/parted.html
BTW: the front-end for parted is Qtparted, also parted and qtparted is usually listed in the packages list of your distro, that is if it isn't installed already.
peace V