Hi there,
Like you said, DAQmx is only officially compatible with LabWindows/CVI 7.0 or later. This link has more information on this compatibility: http://zone.ni.com/devzone/cda/tut/p/id/2931
In addition, USB-6008 is only officially compatible with DAQmx (previously, the plaform was Traditional DAQ). You would need Traditional DAQ to work with CVI 5.0, but the USB-6008 doesn't officially work with that.
Someone here might have an alternative solution, but though it seems you need to use CVI 5.0, is it possible to upgrade this?
Ravi A.
National Instruments | Applications Engineer