IDE drive in Firewire external case

Has anyone tried to put a std IDE (40Gb ATA100/7200rpm WD BB400) drive in an ext. firewire case?
Testing under XP Pro, Dev mgr sees the controller as a HDD controller – but no devices listed.
Disk manager of course, does not see it.
A CD-RW is fine; but not the HDD – am I being naive in expecting it to work? does a HDD need a driver of some decription?
Its really bugging,e, as I thought I had a backup solution (using removable bays).
Rob