If you are giving serious thought to being a wedding photographer, either as a full-time or part-time occupation, then congratulations!The job can be one of the most rewarding jobs in the world, but you really do have to have the right set of skills and tools to make it in this business.
Here are the bare essentials to get you started:

• A DSLR camera - A lot of people just getting into wedding photography think that they need to go out and buy the latest and most expensive DSLR, and while that may not be a bad idea it is also not necessarily the most important piece of equipment.
  I know that the previous comment might sound like heresy to the digital-photography elite, but think about your budget and decide if you can really spend a few extra thousand dollars on a camera without skimping on lenses and other equipment.
  If so, then go for it, otherwise keep the money in the bank for a rainy day.
  
• On the subject of lenses - You will need a wide variety of lenses to shoot under a wide variety of conditions.
  Wedding photography can be really challenging in this regard because there will be shots outdoors, indoors under great lighting, and romantic shots with the lights dimmed.
  
• Do not forget the extra equipment - A sturdy tripod, a variety of maneuverable flashes, extra batteries, high-performance memory cards, a laptop or netbook, lights, a studio, etc.
  These are just some of the things you are going to need to buy!Remember that you need to tote all these things around, so do not skimp on quality photography bags!
• About computers - Many modern photographers are really getting into small and inexpensive laptops and netbooks as they can insert their memory cards and run an import of RAW files while they are driving from one shoot to the next.
  Transferring files over WiFi or a wired network is often several times quicker than transferring from a memory card!
• The knowhow and experience - Remember that a wedding is a very special day and you do not want to be responsible for getting poor shots of the big day.
  Not only is this not going to get you paid, you might find yourself at the business end of a legal claim!Be sure that you know what you are doing before you get into it.
  
• Some things money can't buy - Along this same line of reasoning is the set of skills you need beyond the technical knowhow.
  You need to know how and when to catch that look, that smile, that mischievous ring bearer playing tag with the flower girls, and so on.
  You also need a little bit of business savvy and certainly helps to have a few connections to get you started!

That is really all you need to get started.
If you think that you really do not have those skills, then you might want to consider hiring a professional for the big day unless you feel that you can gain those skills and buy the hardware in time.