Windows Backup File Error contains unrecognized data

Hi friends,
Due to feature and updates provided in Windows XP, I planned to upgrade to it. Before upgrading, I was using Windows Millennium Edition (Windows ME) as my operating system.
I did a backup of my important files, but now after upgrading my PC to Windows XP, I am unable to restore those files on new operating system.
Whenever I try to restore that backup, I got the following error.

Unrecognized Media
The backup file contains unrecognized data and cannot be used.
Now this is making a hell for me as I have my much important files saved in this backup and I badly need them on my PC for smooth running of my working.
Please help.
Thanks.
