I recently replaced a keyboard on a Dell Inspirion 1300. It was very easy. I bought the laptop keyboard part as a spare part from ebay. (I fitted it whilst warming milk for the kids - that is how easy it was.)
Look up how to remove your keyboard - I found a manual which explained how to remove mine. Some of the sellers of the spare parts will give you instructions on how to do this.
Iain, October 2012