DirectX + x1950 Memory problem

Hi,
I recently bought an x1950GT 512mb, and its been running fine. I just tried to install FSX and it keeps throwing up an error...
"Flight Simulator is not working with your video card. Verify that you have the latest drivers installed for your video card. Flight Simulator will now exit."
So I googled it, and there was a handy link to a microsoft help page. It said to make sure the most up to date versions of the ATI drivers and directx were installed (which they are) and to run the directx diagnostic tool to check there is a minimum of 32mb onboard memory. Now I have 512mb.. but it seems directx doesn't detect this, and so therefore neither does FSX, or presumably any other game I try to install.
I'm running XP SP2. The error is to do with DirectX not detecting the fact that my graphics card has onboard memory, not the system memory. In fact its not a blue screen/crashing type error, its just a message that comes up on the splash screen before I'm even in game (it won't let me in at all!)
Looks like there might be something funny with the card? in the DX diagnostic tool it says that DirectDraw and AGP texture acceleration are "not avaliable" :S
any help would be greatly appreciated.

Its probably some thing similar to what i had the first time i played(tried to play) halflife for some reason the game just didnt like the installed drivers the game has a link to the latest drivers which worked but all the wireframe work was visable on peoples faces so i went direct to the ati site and downloaded the latest drivers and the previous release also from memory it was the previous released version that worked properly in the end. Hope it helps

Mactronix

Some games come with direct X on their cd,OK?
Dumb question here,,you don't have on board video ?? is it off,did you remove the previous drivers???)