My suspicion is that it's actually the bootloader that's messed up
rather than the logical volumes themselves.  (most likely) Grub is
configured to point to the old drive, and doesn't find anything there.
 So what you'll need to do if that's the case is to use
grub-setup/grub-install to update the Master Boot Record to know about
your new drive, and then possibly the menu.lst to know that the system
itself moved too if it doesn't figure that out automatically.

 - Tony Yarusso