Taken from the old site a post that I have often referred to and am sure many found useful , hope you dont mind Sticks ,

Right - sorry for the delay and also apologies in advance if I'm about to tell you something you already know!

 
It's worth explaining what a 'bridge' camera is for starters.  This is a camera which has styling like an SLR but has an integral zoom lens, usually with quite a big range.  There are some coming out now which are totally automatic with little or no manual over-ride.  If you want to photograph bike racing avoid these.  You will need something that has the ability to control the shutter speed and also has autofocus tracking.  As with any product there are pros and cons.
 
The advantages of a bridge camera are:
 
* Usually more compact than an SLR
* Integral zoom lens with a very wide range, often from very wide angle to extreme telephoto
* Cheaper than a digital SLR outfit
 
The disadvantages (compared to an SLR) are:
* Inferior picture quality
* Slower operation
* More difficult to focus manually
 
I'll explain in more detail.  The image sensor in a bridge camera is tiny compared to an SLR, so if you had an SLR & a bridge camera both with 10 megapixel resolution the pixels on the bridge camera will be much smaller.  This makes them less effective at doing their job, which is to capture light.  In use this means that a bridge camera will be less effective in capturing shadow detail and will be more prone to burning out highlights.  A small pixel is also a noisy pixel, so bridge cameras will be more likely to suffer from image noise (coloured blotching & speckling in the picture).  In a nutshell, bridge cameras will give perfectly acceptable image quality in optimal conditions but if it gets very bright & contrasty or dull, the SLR wins every time.  When looking through an SLR viewfinder you're seeing a true image via a mirror/prism arrangement, which makes focussing manually (and you will need to at some point) fairly easy compared to a bridge camera which uses a miniature LCD screen.  The wide range lenses bridge cameras have are more prone to distortion than shorter range zooms but this won't be especially obvious unless you shoot subjects with lots of parallel or vertical lines.  They're also more prone to chromatic aberration or 'purple fringing' which can occur around the edges of high contrast areas in the shot.
 
An SLR, even a modest one, will usually out perform any bridge camera in terms of picture quality and response speed.  Bike racing is a difficult subject to photograph and you don't need to be making life any harder for yourself than you need to!
 
Pixels - don't worry about how many a camera has.  Anything you get now will have more than enough for most needs.  Some of the 12x8" shots I'm showing in the RRS.com exhibition at St Ninian's were taken on a 6 megapixel Nikon D70.
 
As a Nikon user it grieves me to suggest this but if you look on flea bay for a Canon EOS 400D with 18-55mm lens (for every day stuff) and a Canon 75-300mm USM lens (for racing) you may well get them within your budget and it will be a good starting point.  The USM bit is important - it indicates that the lens has a fast focussing motor which you'll need for racing.  Nikon's version is called AF-s and Sigma is HSM.  (Canon lenses will only fit Canon cameras & Nikon lenses will only fit Nikon cameras.  Sigma is an independant brand, so if you got one of their lenses you'd have to make sure it's the right fitting.)