Bruce Schneier has an interesting post on setting up an air gap computer. It seems simple: just never connect your computer to the Internet. The problem is a completely isolated computer isn’t much use unless all you want to do is play Reversi or solitaire. To get any useful work done you need to move files onto and off of the computer.
At first glance it’s hard to see how a “normal” person would even need such a thing. But once Schneier became involved in the analysis of the Snowden documents he needed to isolate and protect them. When the need presents itself, you have to consider how best to protect yourself and your data.
Schneier began by buying a new laptop from a big box store and taking it to a friend’s house to download the software he needed. After that he never connected it to the Internet again. Still, there is the need to transfer data to and from the machine. It’s not nearly as easy as it seems.
Follow the link the see how Schneier handles the problem. The real meat in the post is in the comments. Almost everyone said, “Yikes! You’re using Windows? You should be using Linux.” That’s probably good advice but not too helpful. The other comments represent some useful advice. It’s a fairly long post with a lot of comments but it’s definitely worthwhile if you have to do something similar.