depends on your video card. do you have an nvidia card with detonator drivers? go to 'display properties' > 'settings' tab > 'advanced' button > [video card] tab > 'additional properties' button > 'direct3d settings' tab... there you can make limited choices concerning direct3d.
if you don't have an nvidia card, i wouldn't really know... you can look around in the same area as i described above, though.
if you want to simply view in-depth directx information, type "dxdiag" in the start menu > 'run...' thing.