How to change type of root file system(Ext3 -> ReiserFS) - please read for more detailed question

[VJ]

Hi,
    I am trying the following method to get Norton Ghost Like facility in
Linux. I installed linux (KnoppyMyth / Ext3) on a partition(hdb3). Boot
loader can be ignored at this moment because I am using Grub which is
installed on another hard disk partition(hda1). There is another linux (FC2
/ reiserfs) installed on hda1. Now, I tar+bzipped the contents of the mount
hdb3 while running FC2 from hda1. This way I got all the files from hdb3
which I can restore anytime on hdb3 again in case my hdb3 gets hosed.
    This technique works as long as I keep the file system on hdb3 as Ext3.
But if I change it to reiserfs and then restore thoe whole thing, the kernel
panics and complains about not being able to mount the root file system. It
complains as if it is trying to mount a FAT partition. I understand that
this has to do woth initrd thing, but I am unable to do so cos I do not have
knowledge about that.

Kindly suggest if this thing is possible at all, and if yes, then how?

Thanks and regards from

VJ