Running two USB-6251 simultaneously on one computer

[DAQ question]

I am collecting data using two USB-6251 boards hooked up to one laptop.  I am trying to figure out how to synchronize the data - the data from the two boards are logged at different times and don't line up properly. 
Any suggestions?
Thanks!

[Wayne.C]

This should be a good starting place.  Pay particular attention to multi-device syncronization.  http://zone.ni.com/devzone/cda/tut/p/id/6829