DX( and DX10 compatiblity

[-=BigD=-]

I'm going to upgrade (rebuild really) my PC at the end of the summer (apparently it is summer now).
Now I'm thinking of going for one of the Vistas as the OS, and I'm thinking of getting an 8800 GTS to take advantage of DX10 games that are starting to coming out. I've found a list of games that are compatible with Vista but am I also right in thinking that games using DX9 will also work with DX10 as its backward compatible?

[kempie]

DirectX 10 is not backwards compatible. However I believe that a version of DirectX 9 is embedded into Windows Vista in order to maintain backward compatibility.