by Andrew on Tue Mar 23, 2010 12:31 pm
In very simple terms, you need DirectX so that your video card and other multimedia devices will work properly with NBA Live 07 and other games. Normally, games will install DirectX automatically though if you have the same version or later already installed, the installation will skip this step. As you've discovered, you can also download it from the Microsoft website and install it manually.
In short, it's a required component when it comes to video cards and 3D games so yes, you need it and no, you can't use something else.
Clearly there is some corruption or security/permissions problem that's preventing you from installing DirectX properly, resulting in the failure notice and error message that you're receiving. I'm not familiar with the exact solution but you might want to run a Google search along the lines of can't install directx cabinet file can't be trusted and your operation system (Windows XP, Windows Vista, Windows 7) as I'm sure other people have run into the problem and there's a step by step solution out there somewhere.