On-Screen Keyboard a great tool.

Before you go through this page, I suggest you to book mark this web-page because it may help you in future.

On-Screen Keyboard is a great accessibility utility that displays a virtual keyboard on the computer screen that allows people with mobility impairments to type data by using a mouse or joystick. This utility really helps us when we have issues with few sticky keys on keyboard.
With this on-screen keyboard; you can use your mouse to type in any text environment, including chat, email and word processing programs. You will need to configure it for "Always On Top" in order to use it with your text environments.

Additional information:
http://www.microsoft.com/enable/training/windowsxp/usingkeyboard.aspx
http://www.microsoft.com/windowsxp/using/accessibility/oskturnonuse.mspx
Onscreen virtual keyboard benefits for.....
1) Developers
2) Touch Screen Users
3) Disabled Users

Here you can download JavaScript for Onscreen keyboard.