Vista cannot see backup sets

I have a DELL XPS 420 with a Maxtor 250GB ext hard
drive... I did a 'Complete PC Backup' to B: drive (The ext Maxtor)
Next, I rebooted and used the system repair from the boot menu... this
formated my hard drive and set everything back to the DELL factory
defaults... re-installing Windows Vista Ultimate, Office 2K7, and all the
other DELL junk...
Now, I'd like to restore the computer to before the DELL repair... the files
are all still on the B: drive, I can see them there...
However, when I go to 'Restore files' -> 'Advanced restore' -> 'Warning -
Continue' -> only the 'Files from a backup made on a different computer.' is
enabled and already has a tick in the radio button -> 'Next' -> 'Looking for
backup devices...' -> I select B: drive -> and it tells me "Windows cannot
find an backup sets on the selected device"
--
Love is very patient and kind, never jealous or envious, never boastful or
proud, never haughty or selfish or rude. 1 Corinthians 13:4 - 8, 13