While the video card has the bare minimum 512MB of video RAM, it is not going to run the Alpha very well at all simply due to the really low end GPU.
It has less than half the performance of our baseline video card (NVidia 9800GTX).
To even have a chance of running the Alpha, you need to turn down the Maximum Texture Size to around 512 and check all the "Disable" options in the "Graphic Detail" panel, along with setting the environment mapping slider to "None".
Also return the field of view back to 80 to reduce the amount of work the video has to do. Might even consider running at a lower resolution (1280x720).