ok....so I lost a rather lengthy response a few minutes earlier because my computer was sounding like it would explode and the words were lagging behind a bit before appearing on screen!
software - it depends on what you want to do with it. You can certainly - pre-plan your quilt. You can also do a layout and play around a bit - but I haven't figured out a way to swap blocks directly. I will try to type later - computer acting up again