In the beginning there was DOS and then came Windows version 1. (I am aware that there were other operating systems available such as MacOS and OS2 etc).
Then came windows 2 and windows 2.1 and although little icons were starting to appear they were not fundamental to the use of the system in anyway whatsoever.
In Windows 3 icons became more prevalent and were used to start applications.
Icons on the desktop are not arranged in any particular way and the system is not reliant on them.
In Windows 7 again nothing really changed.