Hello Dennis,
DataSocket does allow you to connect to OPC servers. You may find the information at http://www.ni.com/opc of interest, specifically the link to "ComponentWorks DataSocket".
For extensive information on OPC compliance and programming with DataSocket, try the following URL: http://zone.ni.com/
Then click on RESOURCE LIBRARY >> LABWINDOWS/CVI >> CONNECTIVITY >> DATASOCKET >> GENERAL
I hope this online information fully answers your questions.
Jeremiah Cox
Applications Engineer
National Instruments
http://www.ni.com/ask