DirectX using BootCamp

Hey, i'm getting my first Mac like next week. It's a Mac Pro with a x1900 XT card. I was thinking about installing Windows Vista Home Premium using BootCamp. I was wondering if I should download DirectX 10 or just stick with DX9? That's the only thing I have a question about reguarding this

no answer

For starters, Vista comes standard with DirectX 10. However, the X1900XT is not DirectX 10 compatible. Therefore, you're "stuck" with DirectX 9.

It won't really affect you right now as there are no DX10 games available yet, and even when they do become available, your video card doesn't support DX10. So you really don't have to worry about it.