McDonald Marketing Research United Research Scam, Internet

I received a letter from McDonald Marketing Research, Inc. signed by "Linda Johnson and David Zimmerman, and a check for $3,780.00 from a "My Credit Union" endorsed by Barbara Miller.  This was for $400.00 for me, $240.00 for Western Union, and the balance refunded.  It was supposed to be 2 "training assignments," for a customer service position.  The similarity to the other post by the unemployed gentlemen was too close.  The envelope was mailed from Canada, the check is from Watauga, Texas, and the company is in El Paso, Texas.