I got one of those calls, and here's what happened:
Hi this is the windows support team, we believe that you have malware on your computer and we need you to type some numbers in the run box to delete it.
OH, YEAH! WHAT'S MY SEREAL NUMBER?!
Uhhh... Uhhh...
WHAT AM I RUNNING?
We cannot obtain that information.
WRONG!!! MAC OSX 10.6!
Lol