I believe it's possible to prevent copying of downloaded Microsoft text files, in the form of a book, by having them 'locked' to the IP address of the particular PC to which they are downloaded. Can anyone please tell me how to perform this function? If that's not possible - any other suggestions for protecting plain text from piracy - other than PDF?Thank you.

Wouldnt you need to take into account the fact that not everyone has static IPs? So you would need to use a range and make sure they are not using a proxy or whatever. Plus having to actually store the IP information somewhere so it can be checked.

and how would you ever incorporate something like that in plain text?
text is text, unless you have some custom reader software that incorporates such capabilities and a custom document format that contains that information you're not going to get anywhere.

And you can be certain that the criminals will crack your "brilliant" encryption/protection scheme within minutes, hours at best, of you releasing your software.