Hi,
You may find the following website very useful: http://www.ni.com/support/imaq/
from here you can follow links for installing NI IMAQ hardware (PCI-1407), what to do if you cannot see your card under Windows NT, and if you need to, changing Windows NT PCI Bus Mastering. Follow the instructions and you should see your card. There are no options for adding the card from LabVIEW, and you should ensure that you install the ni-imaq driver first before installing any hardware. The latest version is 2.5.2 and is available for download free of charge from the ni.com web site.
If this does not help, please contact National Instruments Technical Support.
Sam