ScummVM, the open-source interpreter for classic adventure games, just announced official support for the SCI engine behind classic Sierra adventures like King's Quest V. They are currently testing all the supported games, and if anyone here has the time, inclination and one of the titles, the daily builds for Macintosh, Windows, Linux and other platforms are available at the bottom of the downloads page.
There's also a wiki page listing all the games being tested and the number of complete walkthroughs performed on each one. After completing one of them, the test can be reported on the forums, along with the game's version, language and platform. A word of warning: they don't allow any discussion about piracy and illegal copies on the forums, including abandonware. Any bugs encountered can be reported as well to the appropriate SourceForge tracker.