dude, first what is ur budget? secondly even if u had say a spare 7k for a new d3 do you have any experience in photography?
im not trying to put u down in anyway...but i feel maybe you shld take baby steps to acheive your goal. decide on a system that u feel comfortable with both in terms of budget and performance (depending on your criteria such as build, egronomics, image quality, lenses available...etc)
do research...read online stuff. its not as simple as u put it. one doesnt become a wedding photographer overnight. depending on your learning curve, u could take months.
read the forums..post up stuff or join one of the clubs and go for shoots. after u have familiarised yourself with the basic principles of photography try to attach urself to a wedding photographer. its going to be dead hard to find someone if you dont even have basic knowledge and a portfolio to start with.
btw the answer to your question is, a dslr because high resolution, flexible.
flexible in terms of control the lighting. lastly the ability to change the lense. although im not saying equiptment is a substitute for ability, im saying that luis hamilton wont exactly be where he is if he raced with a saloon car.
most direct way is to enroll in a Wedding Photography course.
However, be warned, such courses assumes you have a good foundation in basic photography already. I hardly ever hear of 'Beginner Wedding Photography Course' .
Dun worry about equipment first, a good instructor will advise you what to buy based on your shooting style. Also, better to have the knowledge and no equipment than the other way round ...right?
Good luck. Dun feel ppl here try to put you down. One of the most basic requirment of a photog (especially wedding) is to have thick skin. The amount of 'suan' you will get from clients and their friends/family will be a common thing you have to deal with when starting out.