This may seem paranoid, but, what kind of protection is recommended before handing out prototypes for playtesting? I am just about at this point with Corpwar and I don't know if I should worry about handing out rule books without copy protection. I have dozens of dated files on my computer showing that I have been working on this for a couple of years, but, I do not know if this would provide me with any protection on my idea.
Xan
This topic has been covered quite a lot in the past (and in some heated debates as I recall). Try using the search function and searching for non disclosure or NDA and you should find plenty.
Personally, your level of protection depends a lot on the people with whom you're playtesting. If it's family or close friends, then you probably don't need to worry about an NDA with them (you know your family and friends well enough to know if there would be a problem).
For blind playtesting, an NDA is a good idea since you shouldn't know the people that are playtesting your game.
Overall, protect yourself with a copyright if you want a degree of protection. Nothing is bullet proof, but ideas are a dime a dozen. I have never heard anyone on this board complain that their idea was stolen. Chances are you won't have any problems.