First, I think the idea has merit. Basic human instinct is to survive, which means you must defend yourself from the dangers of the world... The RIAA being one of them. I don't use Kazaa myself, but the virus idea is a nice defense for those who do.
Second, I've heard the RIAA isn't going after the "small-time" people who download the music anyway. Their real targets are the "big-time" people who upload it, especially over very high-speed connections. So if all you do is download, I think you'll be pretty safe. If I'm wrong... use the virus.
