OldComputers.net is a great site with lots of information on the history of personal computers. The site is organized around a timeline of computers, starting in 1975 with the MITS Altair 8800, ending in 1989 with the Macintosh portable, and covering everything in between. I used a lot of the computers mentioned on the site and still remember most of them fondly, so this was quite a blast from the past...