Hi Marcin
Welcome to Legwebmasters I am sure you will be a valuable contributor here - and your English is way better then my Polish
I don't have an answer to your very valid question. In our case, sad to say, it's just time. Whatever we do, will will never stop the theft, the best that can happen is that we try and keep it to a minimum.
Policing the web is a very time consuming process. We work on a principle that the time is best spent marketing the sites to get maximum traffic and sales. It's a bit like football (soccer to my American buddies) I would rather win 6-5 than defend like crazy and finish 0-0.
On a sober note I think it's important that we all stick together. If you find stolen content, as you have Marcin, post it here and we will all act. One thing I have done in the past is post on bigger boards with major players there. They often have the resources to tackle the issue more forcefully. I even have contacts on one or two of them that will happily bring a site/server down if we ask nicely and wipe the content. Sounds extreme but we have to do what we have to do.