GoG offers they're registered users a free Christmas Present in the form of some oldschool graphic adventure. Tex Murphy 1 & 2 is Free until December 24th and can be downloaded today, that's Mean Streets and it's sequel Martian Memorandum, all XP/Vista/Win7 ready. Tex is a character and the series is definitely worth checking out, cheese notwithstanding.
The roots of the series is here, but the final three games really show the heights that early game designers reached in story and production for a time that games were considered cheap and inexpensive to make.