Am I being scammed or what?

I receivedd a letter in the mail saying I had won the sum of $120,000.00 from the 2011 Customer's Appreciation Lottery Draw in conjunction with the North American sweepstakes Association. there was also a check in the amount of $3,700.00 from a company called NMTC, INC. d/b/a Matco Tools. I called the number in the letter she read the serial number to me that was in my letter. She said to deposit the check into my bank account. then call her back and she would tell what to do to recieve the rest of my winnings. i gave out know information. but I FEEL LIKE THIS IS SOME KIND OF SCAM .