No, the NI 6601 cannot be used with Lookout. The reason is because Lookout uses the the NI-DAQ OPC server to communicate with DAQ devices through virtual channels, but you cannot have a virtual channel for a counter. Therefore, counters (such as the 6601) cannot be used in DAQ OPC, and hence cannot be used in Lookout. The following KnowledgeBase discusses this topic:
http://digital.ni.com/public.nsf/websearch/505D2E9A1617B5F686256A1B00574777?OpenDocument
LabVIEW would be an excellent software option for counter applications using the PCI-6601.
Regards,
Jeff M.