Before your mentioned this, I was thinking that something along these lines is the answer for the small business that wants to keep their software licensing situation legal and under control.
I run my personal Win2000 and WinXP PC's within the least-privileged mode (for security reasons). But I have the Admin passwords for running Windows Update and installing software (I own these PC's.). It's a common misconception that computer users need to run with Administrator (root) privilege.
With Win2000 and XP, there are built-in methods in the OS to assist the business owner's efforts to keep the users within the desired privilege bounds. Unfortunately, the techniques are not common knowledge. There is definitely a need for a simple book/manual on how to set up Windows2000/XP PC's for maximum security and minimum user privilege. Medium and large companies have IT people who possess the know-how to make this happen. But small businesses often don't have dedicated IT people, or they have poorly-trained IT person(s).
You know what, if you wrote such a book I'd buy it. A lot of the computer books on the shelves are nearly worthless. Storage Area Networks for Dummies, anyone?