I have accomplished the same scenario with a couple of tools. I used Clonezilla which uses partimage, and gparted.
First I saved the combined partitions on a reserved drive. With clonezilla you can restore the original partition tables that was on the drive (mbr). And on restore you can decide to restore the original partition table or just leave it alone. If your hdd are the same I dont see a problem with cloning the drive.
There are bunch of options available with clonezilla. I like it because I can save it too a cd and backup and restore drives to another machine using ssh. Very handy tool.
I resize the new partitions with
gparted, which is a Gnome tool. You'll have to find a gui tool for XFCE for ZenWalk, not sure of one for XFCE.
I try to get a close as I can in size using gparted. Clonezilla can restore to a partition that is the same size or larger.
After backing up the partitions I restore with the options (no grub) & (-k do not change partition table from image). This way I can use the new partition tables I created using gparted. Then after restore, I use a linux live disk, and manually restore grub. Since I had grub installed originally, I dont have to re-create my menu.lst or grub.conf. In the live disk I run these commands
Code:
# su
# grub
grub> find /boot/grub/stage1
(hd0,0) <--- This is the location of the menu.lst file
grub> root (hd0,0) <--- This tells grub where the menu.lst file is located
grub> setup (hd0) <--- This installs grub to the mbr
grub> quit
Then when I restart I have the original menu and grub is restored to the mbr