(tdn@bart.) (Mon May 07 10:58 ) {P:0 H:64}
(~) sudo fdisk -l /dev/sda
Password:

Disk /dev/sda: 80.0 GB, 80026361856 bytes
16 heads, 63 sectors/track, 155061 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       31012    15630016+   7  HPFS/NTFS
/dev/sda2   *       31013       31603      297864   83  Linux
/dev/sda3           31604      145800    57555257    5  Extended
/dev/sda4          145801      155055     4664520    c  W95 FAT32 (LBA)
/dev/sda5           31604      141079    55175872+  83  Linux
/dev/sda6          141080      145800     2379352+  82  Linux swap / Solaris
(tdn@bart.) (Mon May 07 11:54 ) {P:0 H:65}
(~)


I have installed a base Kubuntu 7.04 installation on /dev/hda6 with /dev/sda2 as /boot.
Both use etx3.

Then I guess I need to luksFormat /dev/sda5 and then copy the contents of /dev/sda6 to /dev/sda5.
Then update /etc/crypttap and /etc/fstab.
Then I need to change /boot/grub/menu.lst to point to /dev/mapper/root.