XFX 7800GS Nvidia driver 64 bits not working with FS9

Can't get this videocard working under Winxp X64.Tried everything you could imagine, downloaded and installed dozens of drivers from different manufacturers but FS9 won't work!The strange thing is that with an MSI RX800SE (ATI) everything is working well.My specs are:Asrock939DualSataII mobo1 gig pc3200 memoryAthlon 3700+ processor500w PSUGet an screen with on the wrong places the sky with clouds , furtheron the system is verry verry slow, no preview of the plane.Tried every imageble setting within XP and FS9, nothing works.Can't imagine that the ULI chipset is the evil one because Nvida has bought ULI and is supporting ULI on the official Nvida-site; it is working well with ATI.Winxp by itself and the 7800GS are working well, it is just concerning FS9.Who??