Links to basic reference material and resources.

Wikipedia's History of Computer and Video Games.
Bear in mind that Wikipedia is a community encyclopedia that anyone can edit -- including people who don't know what they're talking about, and those who passionately believe something without actually having the facts to back up their points. Thus, I consider a Wikipedia to be a good enough reference for routine class assignments and informal discussions, but for research papers or formal presentations you should look for more authoritative sources.

PBS's The Video Game Revolution: History of Gaming
Requires flash. Not a whole lot of data, but the timeline gives a good overview.

Computer Game Timeline
More detailed, but still just a list of milestones.