http://bit.ly/JoTpcjAlso found this on wiki and found it interesting:
Venomous snakes are often said to be poisonous, although this is not the correct term, as venoms and poisons are different. Poisons can be absorbed by the body, such as through the skin or digestive system, while venoms must first be introduced directly into tissues or the blood stream (envenomated) through mechanical means. It is, for example, harmless to drink snake venom as long as there are no lacerations inside the mouth or digestive tract. The two exceptions are: the Rhabdophis keelback snakes secrete poison from glands they get from the poisonous toads they consume, and similarly, certain garter snakes from Oregon retain toxins in their livers from the newts they eat.
Also from
http://www.reptilegardens.com/reptiles/snakes/venomous/:
It is important to keep in mind when discussing venomous snakes that the "most deadly" snake and the "most dangerous" snake are two entirely different concepts.
Some of the snakes with the most toxic venom – in other words, more deadly - rarely bite people. For instance, the deadliest sea snakes are generally quite docile. The Inland Taipan, the snake with the deadliest venom, has never killed anyone on record. On the other hand, the snakes that kill the most people (most dangerous) have “mild” venoms compared to other venomous snakes.
And
Many people believe the Cottonmouth and the Copperhead to be very deadly. Legends aside, they are not really very deadly at all. The maximum amount of venom a Cottonmouth can deliver is just barely enough to kill a single person. The Copperhead is less deadly still; even if untreated, a Copperhead bite causes death in considerably less than 1% of bites. There is even some question as to whether there have been any deaths at all from Copperhead venom.