Your title is a little misleading, in that these purport to be workarounds to make DX10 games run on XP. But they don't utilise DX10 in so doing. Do not imagine for example, that you can run FSX and get VC self-shadowing, on an XP installation.
These guys are probably a hoax. While they claim that they'll bring DX10 to WinXP via opengl wrappers (basically like the linux guys bring dx to linux) this is months old with nothing else than a claim that an alpha version exists. Recently someone warned me that their site is infected with a virus. So much for that story...