I recently had my nvidia card go for a burton and by recommendation had fitted a radeon hd 5750 card but when i try to load FX I get the following message "graphics card does not meet min requirements for shader support producd requires geforce3/radeon8500 class or better . does this mean I have wasted

No, you don't have wasted your money. This is most a driver related problem and your new card of cores will run FSX.Which Windows Version do you have?Did you first uninstall your "old" nvidia drivers and after a restart do you clean up the driver with driver sweeper or so?Which ATI Driver Version do you using. Install Catalyst Version 9.10 if you do not have done this already.