To view appropriate Khmer Unicode, you need to have Khmer Unicode fonts in your machine with enabling the complex script.
The good Web browser for Khmer Unicode today is Internet Explorer 6+. If you use other web browser, visit www.khmeros.info for more information.
Now click here to download the latest Khmer Unicode Install Program (currently it is version 1.2.5) and once it is finished downloading, run the program. When you run it you should see something like the following:
Click "Next"
When this box pops-up click the "Complex & kbd" button (this can take a few moments to install, so please be patient). It is possible that you will need your Windows XP cd at this time - so if you are asked for it, please insert it into your cd-rom.
When the text "Complex script enabled/Keyboard layout added." appears click the "Close" button.
To finish off the installation, click the "Exit" button.
Now you should see a new button in the lower right corner of your screen saying either, "EN" or "CA". When you want to type in English, make sure "EN" is showing, and when you want to type in Khmer Unicode, make sure the "CA" is showing. To switch between the two langauges, you can click on the button and select (like the picture above shows), or you can press the "Alt" key and the "shift" key which is on the right hand side of your keyboard (if you press the "shift" key that is on the left hand side of your keyboard it will not switch).