D300, 40D, 7D, 550D, 500D, if your life revolves around these numbers, then yes you do have the buyer's dilemma. A state where you can't figure out which product best suits you, frankly because all of them look good around your neck. In this state, there is only one thing to do to help you make up your mind, read on!
Let's take it from the top, understanding the working of a DSLR will help you in making an informed choice so that you don't end up buying a camera and regretting it. Basically, every digital SLR works on the same principle: what you see is what you get. SLR stands for Single Lens Reflex, meaning that there are mirrors inside your camera that help in showing you exactly what the camera's lens is seeing.
So, we've established how a DSLR works; now coming to the selection. First, you have to determine what kind of use you'll be subjecting your camera to. For example, if you are a sports photographer, you'll have to take photos on the spur of the moment. In that case, you need Canon's 40D or Nikon's D300, which give you a speed of 6-7 photos per second. On the other hand, if you are a beginner and are learning photography, you should opt for Nikon's D3100, which actually shows you how changing the settings can affect your photograph.
Nikon' newly launched D3100 camera is bundled with some attractive features.
You also need to consider lenses with your DSLR purchase, because lenses may actually change the view and quality of the photograph you are going to shoot. You have option to choose from wide variety Zoom lenses, or opt for wide angle lens, some work may also require you to shoot very close photographs With the help help of macro lens.
There are a number of cameras to choose from for different styles of photography. There's one for macro, one for action, one for landscapes and so on and so forth. shutter lag time can actually how you can use you camera. Choosing your style will take you a long way towards uniting you with your dream machine.
After you've defined your style, start looking for cameras that complement your styles. Learn some DSLR jargon, like aperture, shutter speed, ISO etc. There is no harm in being informed, after all, is there?
The above are all you need to choose the camera that is right for you.