Excel VB Programming - Stopwatch Macro

I need to create a series of macros in Excel that will perform stopwatch functions. There will need to be eight buttons. When one is pressed, it will start the stopwatch associated with that button. When any other button is pressed, the first stopwatch will stop and another will begin (the one associated with the second button). The macro should drop the time difference between the two button presses in a cell in a column associated with the first button. The same functionality should exist for all the eight buttons: Whenever one is pressed, the previous stopwatch ends, a new one begins, and the time difference is placed in a cell. Looking for someone who is an expert in Excel, Visual Basic, and has worked with timing functions in Excel before.