Last week, I had to do some testing and development on Windows. I usually work on Mac OS X with a virtualized Windows. This time, I decided to boot into Windows (using Bootcamp) for the sake of performance.
The task took about 2 days. During this time I discovered that my productivity greatly increased. Why? Very simple: I have a very minimal windows setup. I don't have any decent browser installed other than the very basic Internet Explorer (not even 8). Needless to say, it has the default bookmarks. I don't have an email client. I don't have a twitter client. No server monitoring tools. No Growl notifications. Not even my todo list (I use OmniFocus which is Mac & iPhone based).
I was still connected, since I do have my iPhone with all of the above, but it's a more constrained experience. It takes too long to write emails or forum posts. I can still check my emails or read some tweets, but the main work area is clear of distractions.
So, there you have it: if you want to "disconnect" and work distraction free, you can start by preparing a second boot for your machine which has minimal set of tools installed and no connectivity. Switching boots (shutting down and restarting) usually takes time, so you probably won't do that just for casual procrastination.