http://www.gog.com/Good Old Games, for those who don't know is a digital game store that offers many old games prepackaged to work on modern systems (including win7 64-bit)with no problems. The new installers are done by GOG themselves so they aren't like the half-assed Quest XP collections.
They just announced that they've made a deal with Activision, (Sierra --> Vivendi -->Activision) The first adventure game that they are selling from the Activision catalog is Gabriel Knight: Sins of the Fathers for $6. They say we'll see more over the next few weeks.
As with all GOG games, there is no DRM. No activation and you can download the files all you want. Including Wallpaers, avatars, and manuals.