As mentioned, start with Steven Kent's
Ultimate History of Videogames. It's an entertaining overview and is chock full of anecdotes. Lots of fun and plenty educational.
Now, if you decide that's not enough and you need a detailed timeline of the video game industry, pick up Leonard Herman's
Phoenix: The Fall & Rise of Video Games, preferably the second edition. Herman goes into absolutely excruciating detail, so while it's not the sort of thing you want to sit down and plow through it does make for a useful reference, on the off-chance you wanted to know not just the year the ColecoVision was released, but the month. And, even if it ain't a page turner, Phoenix is fun to just flip through. The second edition provides a few illustrations to break up the infodump.
If your coffee table is looking a bit loney, suplement your gaming book diet with Van Burnham's
Supercade: A Visual History of the Videogame Age, 1971-1984, which is chock full of gorgeous photogrpahy and fun retro illustrations. It's awesome.
FnordChan