How do I detect if Graphics Drivers loaded?

I'm getting weird feedback from some of my users that have antiquated machines without graphics drivers. They say that when playing the game, nothing shows, but the music and sound effects of the MainMenu start playing.

Looking through log files, it seems that none of the Graphics drivers loaded, but it did not assert fatal and end the game like it seems should happen in winWindow.cc:

// If no device is specified, see which ones we have...
if ( !Video::setDevice( Con::getVariable( "$pref::Video::displayDevice" ), width, height, bpp, fullScreen ) )
{
// First, try the default OpenGL device:
if ( !Video::setDevice( "OpenGL", width, height, bpp, fullScreen ) )
{
// Next, try the D3D device:
if ( !Video::setDevice( "D3D", width, height, bpp, fullScreen ) )
{
// Finally, try the Voodoo2 device:
if ( !Video::setDevice( "Voodoo2", width, height, bpp, fullScreen ) )
{
AssertFatal( false, "Could not find a compatible display device!" );
return;
}
}
}
}



Any suggestions of what I should try? Also, does anyone have a quick way of detecting that there's no graphics drivers, and instead open up a notepad or browser window prompting them with more information of how to install it?