There's no doubt, the best way to explain someone who needs to do anything on their computer is to show it, but that's difficult if the other person is not with you,or at least it was difficult until we found Desktop Activity Recorder. Desktop Activity Recorder is an application that will be perfect for both you and your friend or client because he'll see what to do and you will not have to break your mind to explain it. It's totally free and it allows you to record the screen activity in a .avi file that can be played on any computer. Choose if you'll record full screen or only a part of it. Save the file as AVI or SWF, adjust quality, insert audio and even make notes, it's great and very easy to use. Have it in mind if you need to explain anything.
