The destination for an NDMP backup must be another NDMP host. Windows machines won't normally be one.
Further, since NetBackup does not control the data within the NDMP backup, this is only supposed to work if you restore to another machine of the same "type" (for instance from a Network Appliance backup restore onto another Network Appliance box).
The NDMP data is opaque to NetBackup, so the Windows client would not be able to decode the data. Different vendors use different schemes for serializing their data.
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Darren