This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
There are many diagramming software which will help you to draw flowcharts and other diagrams; however, I use Microsoft Visio Professional to draw flow chart and other diagrams since it best suites my need. And it is also compatible to Windows XP.