Question : What is First Normal Form (1NF)?

My understanding is that a table is in first normal form (1NF) if every attribute 'depends on the primary key'. Is this correct?
Say you had a Drivers table with fields License# (PK), Car1 and Car2 (to accommodate driver's with two cars). Since you can swap Car1 for Car2, nether depends on the PK. Does this mean it is not in 1NF?
On the other hand, if you had a Drivers table with License# (PK), MainCar and SecondCar, now you can have only one value for each car field. Does this mean it is in 1NF?

Answer : What is First Normal Form (1NF)?

see this link
Description of the database normalization basics
http://support.microsoft.com/?kbid=283878