Vertex Shaders

[Zephyr]

Hi, I have a few year old system that was upgraded to Windows 7 (Yay student deals) However, when I try to play Penumbra, Black Plague, it says that my card does not support Vertex shaders.

I've looked around, it's supported on your site (from what I can tell) and the card does have Vertex shader support. But here's the kick, I can't install ATi legacy drivers for Vista. Every time I try, Windows just detects the card, and automatically installs Microsoft's drivers. Windows could be right in saying that it is the most up-to-date version of the drivers, but it looks like to me, that the driver version provided by ATi is a higher version.

Here some of my Specs.
AMD Athlon 4200+ ~2.2ghz
2GB of Ram
Sapphire Radeon X1650
Driver version: 8.56.1.15

If you need more information, let me know.