LabVIEW 6.x VIs should work just fine in LabVIEW 7.1. If you have a problem opening all VIs in the driver, then I would think that you might be missing a DLL. Click on the broken arrow on a VI and that should tell you where the problem is.
Is the driver you are using a LabVIEW native driver (Plug and Play) or IVI? If it is an IVI driver, you need to make sure that the specific driver DLL and IVI Compliance Package are also installed on the system.