I want to do projects to make my resume more appealing to game companies. So I am going to start buying books. But I don\'t know rather to read DirectX 9 or 10 api books to
I would suggest learning the basics using directx9 and then rapidly moving on to dx11. DirectX11 is harder to get started in than DirectX9 because it's slightly more complex but also a lot of the utility functions in D3DX are no longer there, or have been moved to source code like the effects framework. This is no bad thing, but it does make it signifiacantly more complex to learn as you have to learn a lot more things at once.
Spend 2 or 3 weeks learning DX9 then move to DX11 for "real" work :P
Learn basic DX9 using the fixed pipeline and d3dx for loading models etc. It's a lot simpler than DX11 and much better documented, and you'll get a triangle and then a model on screen very much faster. Play with that until you completely understand the basic concepts and tranformations.
But then rewrite it all using shaders only. You'll need to use them in DX10/11 anyway but it's a lot easier to learn when you already have a working framework of code, and it's a lot simpler to get that working in DX9.
Once you have that working, learn DX11. You'll have to switch math libraries. You'll have to invent your own model formats and loaders. You'll have to either invent your own effects framework or use the example one, but they are all much easier now you already know the basics of 3d and programming shaders.