The link that I used previously for my D54250WYKH is gone too. Try this: https://downloadcenter.intel.com/product/76977 It's for the kit but the drivers should be the same as the bare board. I notice that some of the readme files in the updated graphics drivers are dead links. So maybe (hopefully!) they're just in the midst of a reconfiguration.
Apparently the website has come back. I can find the drivers normally. Got nervous that they removed support for the D54250WYB. :-)