Just downloaded and tested your Compare It! product. VERY NICE. I had been thinking of writing my own. May just skip that now. I found two minor issues when doing some basic testing:
1) The status bar at the bottom of the program does not re-draw itself as it should. If it becomes covered (via auto hide of taskbar for example), it may not be re-drawn and the boxes appear empty.
2) The right hand compare pane and toolbar re-paint themselves “strangely” at times. It has some very jagged edges as other program windows move across these areas.
Also, can the overview bar down the left edge be turned off?