To run it anyway (this will only beat the launcher boss, it won't make the game run smoothly), install, find a file called D3Prefs. Change 'DisableTrilinearFiltering' to 1 and change HardwareClass to 1. Then run the game launcher and when you press play you will get that same video card warning, but press escape and the game will launch.
If you can't find D3Prefs run the launcher, press play. On the screen that says your video card isn't good enough press escape. You should get a white screen, which you can then close. Then go back and find D3Prefs as above.