On Monday, RealNetworks, the digital media company in Seattle, will introduce RealDVD, a $30 software program for Windows computers that allows users to easily make a digital copy of an entire DVD — down to the extras and artwork from the box. A vibrant movie rental market makes the threat of widespread DVD copying even more ominous. If people who lack technical knowledge can easily copy DVDs, Hollywood worries, they will stop buying DVDs and instead simply visit the local Blockbuster to “rent, rip and return.” To stave off this outcome and protect what is now $16 billion in annual DVD sales, studios and consumer electronics companies have enveloped their discs with encryption that is intended to prevent copying. The software, which will go on sale on Real.com and Amazon.com this month, will allow buyers to make one copy of a DVD, playable only on the computer where it was made. The user can transfer that copy to up to five other Windows computers, but only by buying additional copies of the software for $20 each. The software does not work on high-definition Blu-ray discs, which the movie industry has even more aggressively sought to protect from illicit copying.