Hi GICD-
NI-DAQmx Base will usually list plug-in PCI cards as PXI, but the card will still function properly when you program with the driver API. The problem you're seeing with the NI-DAQmx Task Configuration Utility is that M Series devices are not supported for configuration using that utility. For this reason, you will need to develop your application using programmatic task and channel creation as shown in the "dynamic" shipping examples from the LabVIEW example directory.
You may also be interest to know that NI just released the full-featured NI-DAQmx 8.0 driver for Linux. If you have the option to upgrade to one of the supported ADE's (LabVIEW 8.0 or C/C++ with gcc) I would encourage you to try the new driver for enhanced functionality and performance over NI-DAQmx Base.
Hopefully this helps-
Tom W
National Instruments