These are the Novacons, part of the Novasuite. In fact, these are the icons that inspired the Novasuite.
A selection from a large collection of icons for Windows is packaged and ready for your consumption, critiqué, use, etc.
This package contains 98 fully alpha blended icons with which to brighten up your desktop. All icons include the sizes 16×16 through to 128×128.
So download, install and enjoy.