Lance,
This really is a misnomer from our mothers and grandmothers. Whenever I had the nausea and vomiting as a child my mom would say that I had "the flu". And in small children that could be the case because fevers in children have nausea and vomiting as a secondary symptom. However, it's usually something like salmonella that causes those symptoms in both children and adults.
"The flu" is caused by the influenza virus...it causes cold like symptoms, but they are on a grand scale. Usually, I can feel I have a cold coming on for a couple of days, with the flu, it hits you in about 2 hours. Seems like one minute you're fine, and the next you've been run over by a semi-truck and someone else has beaten you with a baseball bat from the inside out. You'll have a fever (sometimes quite high 102-104 which could cause dehydration), stuffy head, runny nose, chest congestion, cough, headache, body aches, fatigue, no appetite...it's NO FUN! I got the flu several years ago. I was able to function out of bed for about 1 hour each day, and then it was back to bed for me for and it was like that for a full week! It was 3 weeks before I felt myself again. I don't EVER want to get that again. so I'm adamant about getting a flu shot every year.
As far as the "H1N1" flu virus, it sounds like it's just a more virulent form form of the virus. It attacks swiftly and viciously. The virus is somewhat airborne, but the majority of people get it by touching something that has the virus on it, and then touching their eyes or nose. The best defense...wash your hands frequently, don't touch your face unless you've just washed your hands, and stay away from those who are coughing and sneezing.
Hope this help explain things a bit.