Modified drivers simply means that the author takes official or beta drivers from the manufacturer and starts to tweak them for either better image quality and or performance. Please bare in mind that the driver manufacturer, in this case NVIDIA, does not support drivers like these.

Make sure you see the readme file before installing these. The new drivers are ready and they are based on the previous official set by Nvidia. There where not many changes since last set except for added cards support and some updated software, but, Why change something that was already good? :P