EC
This is information that should be eye-opening for those being contacted by NCO: http://www.budhibbs.com/debtcollectorpages/nco_financial_systems.htm
Do NOT deal with them over the phone and do NOT give them any information about yourself.
Here are some other links that may be helpful:
http://www.naca.net/debt-collection-abuse/
http://www.budhibbs.com/First.htm