GPU processor: GeForce 9800 GT
Driver Version: 341.95
Version of Direct3D API: 10
Unfortunately, the 9800 GT only has hardware support for DirectX 10. Just having DirectX 11 installed is not enough, the GPU must fully support it.
You should be able to play the Classic version (which is 32 bit, rather than 64, and uses DirectX 9c), but would need to upgrade your video card (if possible) to be able to play the Enhanced Edition on that system.
In dxdiag on the Display tab, the 'DDI Version' in the Drivers section on the right is what the video drivers are reporting for hardware DirectX support. This can be higher or lower than the actual value, though (it should be 10 for your card), so looking up the specs is more reliable.