Anyway I think it's a freaking disgrace XP x64 do not get support for WB.
64 bit XP usage is less than 1% of all OSes, not enough for Stardock to justify the expense of supporting it.
I suspect its less than that. But yes there are insufficient potential customers with Windows XP 64 bit to justify the considerable additional development and testing costs.
Most people with 64 bit XP would have upgraded to Vista 64 or Windows 7 64 by now and both of those are supported by WindowBlinds.