Do you want to use an on screen keyboard?
Honestly, I don’t know why I would use it but, Microsoft includes a utility in XP, that displays a virtual keyboard on the computer screen as an accessibility tool.
To turn on the On-Screen Keyboard click on Start, All Programs, Accessories, Accessibility, On-Screen Keyboard. Or even easier, click on Start, select Run, type osk and click on OK
For more detailed information on this and other XP accessibility options see Windows
XP Accessibility Tutorials.
Some of these accessibility options, might be useful, for those who can not see or hear well and those who have trouble using a keyboard or a mouse; give them a try before looking for expensive ways to do the same type of thing.