PC games sales took a hit last year, according to figures from the NPD group.

According to an IGN article, 2004 saw around $1.1 billion in PC game sales, whereas 2005 closed with a comparatively meagre $954 million. That's about a 14% drop.
These figures refer to sales of PC games sold on CD-ROM, and don't include MMORPG subscriptions, or direct downloads of games. There does, though, appear to be declining box sales at retailers.