when is it acceptable to copy images etc off the internet?

Since the advent of google images, pirate bay, etc it has become easier and easier to find "free" stuff off the Internet and utilize that stuff to ones own end. I have downloaded stuff off of pirate bay simply because I already felt my satellite bill was too high and did not want to pay for extra channels. I have found images and used them to create posters etc for fun. I don't think it is right to pass stuff off as your own for professional purposes. I also believe that people should pay for their movies etc. Sometimes a company's own greed will cause a backlash. Star Choice charges way too much for their service, in protest I download "true blood" off of the Internet. In this instance HBO is being punished for exorbitant fees charged by star choice. But in a world of easy free access to stuff I believe it is Star Choice who is totally out to lunch in regards to it's costs and policies. Internet will soon outpace television, and if cable and satellite providers don't change their pricing to reflect that competition, they will lose. Apples i tunes lowered the price of its music down loads because people stopped buying music at $18.00 a pop. I believe most people are willing to support and purchase art and music, as long as they know the money is going to support that artist, rather than going into the coffers of rich shareholders.