If you saw someone choking or having a heart attack, do you know what to do?

Just wanted to see if most people have taken CPR courses, and would they render aid if have need of be. Some states do have Good Samaritan Laws, were if you fail to support someone in distress and that person dies, you could be held liable for not rendering aid. Also what could be considered if you witnessed an accident and didn't stop to assistance. (?)
Yes, I've been trained in first aid and CPR from the Boy Scouts, the Army, the Red Cross and the Houston Fire Dept.
A being is not obligated by law to do first aid in most states, unless it's part of a assignment description. Some states will consider it an act of negligence though. The law prevents a rescuer who has voluntarily help a victim in distress from being successfully sued for 'wrongdoing.' Its purpose is to save people from being reluctant to help a stranger contained by need for fear of legal repercussions if they made some mistake within treatment. Good Samaritan laws DO NOT require members of the general public to donate aid. The term refers to laws that PROTECT members of the public that grant aid from being SUED as a result. There ARE laws in some states that require ancestors with SPECIFIC training, such as doctors, or law enforcement to offer aid, but NOT the common public.
I would help no matter what the conacuences were even though I taken CPR classes.