We have 6 ladies living in our garden very happily and we get fantastic eggs.
There is a forum on the Practical Poultry magazine web site which is very useful and has loads of information on it. It's not massive, so doesn't take long to look through.
Best advice I can give is to get some books out of the library, or buy some on ebay. These range from the purely practical to the amusing and all are worth reading.
Take time to decide on the housing, such as is there a shed that you already have that they could use, or are you going to buy one. The egloos are popular, but we went for a traditional wood one that we got from our local farm supplies shop (Yellow pages).
You also need to decide on the type of hens you want. Some are prettier than others, such as the special breeds, but they may not be as reliable layers as soem of the hybrids. We have 2 hybrids who lay prectically all year round, but the 'pure' breeds have stopped laying. (Hens rely on day length to produce eggs and the hybrids have this greatly reduced through breeding)
They cost vey little to feed after the initial outlay, but you need to make sure that their food ie. layers pellets, are easily obtainable in your area - farm supplies shop again.
Let me know if there is anything else you would like to know, but I fully recommend it as a hobby as you will never (willingly) eat a shop bought egg again.