There is nothing to "fix", as there is no problem. Windows may come with DirectX 11 and your card may only be DirectX 10, but there is no problem. Windows 7 will work just fine on DirectX 9 hardware as well. The only thing you are missing with your current card is any game that supports DirectX 11, and then it will just fall back to DirectX 9 (or 10 if the game supports it). Number 6 here should help explain it,
Tips on Troubleshooting Game Issues