If you've got a computer that you don't have to share with your kids, then you may not be interested in Kid-Key-Lock. After all, you don't have to worry about them trashing that important report you're working on for the office, or killing your budget spreadsheet. If that's not you, however, read on.
Kid-Key-Lock is a tool that lets you configure how your mouse and keyboard behave. Choose to activate, or deactivate, the left, right, and center mouse button, as well as the scroll wheel and even the ability to double click. You can lock down "regular" keys (alphanumeric and symbols) as well as additional keys (function keys, arrows, Home, End), as well as even various shortcut keys (Windows key combinations, [Alt]+[Tab], and the like). Your little Picasso can draw away without putting the rest of your life at risk. Since it lives in the System Tray, it's easy to bring up Kid-Key-Lock to tweak your settings.
Kid-Key-Lock is a free download. It's a Windows app and should be right at home on systems running WinNT/2000 or later.