a few tips for buying a camera (lot of other stuff if u follow the link)

What are the main features to look for in an SLR?

• Pixel count
For most people, the first feature they notice when buying any camera is the number of pixels it has. This is understandable as it is the feature that manufactures push the hardest in their advertising campaigns because it is one of the few quantifiable features to boast about in a camera. However, pixel count is not as important as many people think.
Any Digital SLR with 6 million or more pixels can easily produce fantastic quality pictures at A3 size, so unless you want to make huge posters, or do a lot of cropping, any of the current DSLR cameras would be good enough.

• Frame Rate
The frame rate is the number of pictures the camera is able to capture per second. Most entry level DSLRs will be able to shoot at 3fps. The semi-pro/ high end amateur cameras are often capable of shooting at 5fps and there are a couple of Professional cameras designed for sports and journalism which are capable of firing at an incredible 8fps.
Most people will only use their cameras in single shot mode, but if you enjoy photographing sports or wildlife then a camera with a faster frame rate can be very useful. This is especially true if you enjoy the ultimate challenge of shooting kids running around the back garden!

• Build Quality + Ergonomics
Often overlooked, the handling can be one of the most important aspects of any camera, especially an SLR. It's hard to get an appreciation of this without actually physically trying the camera but most magazine or online reviews will mention this. The main aspects of the ergonomics of the camera to consider are the hand grip, the viewfinder, and the external button functions. The advantages of a good hand grip and a large bright viewfinder are easy to appreciate. The way in which you access certain features and functions on a camera may not seem terribly important at first but you soon start to realise how useful a good control layout can be. A well designed camera body will have all of the regularly accessed functions available on external buttons and dials whereas a camera of poorer design may have these features buried in menu systems. Again, read the reviews and the camera forums and you will see which cameras are praised for these abilities. Often the biggest difference between two cameras will simply be the way it handles.

• AF System
The autofocus systems employed by each manufacturer are usually very comparable at a given price point in terms of speed and accuracy. As you start to move up the manufacturers' lines of SLRs you will encounter improved autofocusing abilities. These improved AF systems usually go hand in hand with a faster frame rate. This is due to fast AF system being needed most when you are in the same situations that require a fast frame rate such as sports and wildlife photography.

• Anti Shake
Anti shake technology has been developed to counteract blurred pictures caused by camera or hand shake. This technology has been available in lenses and camcorders for a few years now. Nikon and Canon have a range of lenses with this technology which can be used on their SLRs. Recently we have seen other manufacturers build sensors into their camera bodies which work on the same principle as lenses, using gyros to detect movement and then shifting the sensor slightly to counteract that movement and produce a sharper image. This is most useful if you do a lot of work with longer focal lengths or in low light.

• Anti Dust Mechanism
This is another recent development in DSLRs. Every time you take the lens off the camera small particles of dust will inevitably enter the camera. When the shutter opens it is possible for the dust to settle on a filter across the front of the digital sensor. When you shoot with a narrow aperture it can be possible for small specs of dust to appear on your pictures. Whilst you can clean the sensor every few lens changes with a bellows blower or sensor brush, it is a great help if you have one of the integrated dust prevention systems. The best systems shake the dust off the sensor every time the camera is powered on or off and have adhesive pads which prevent the particles settling back onto the sensor. If you are worried about cleaning the camera's sensor yourself then these systems can be quite useful.

• Memory Card Type
One other main factor to consider is what type of memory card the cameras use. Most take Secure Digital or Compact Flash cards. The difference between them is insignificant, but you may have a collection of one type already so this may rule out certain cameras. If you are upgrading from a compact camera then you may well have SD cards already, but if this is your first digital camera then the type of media it uses is less important.

link:http://www.parkcameras.com/article/mcs/art/38/#whatisadigitalcamera#whatisadigitalcamera