Re: How good is this build
Take it easy there kiddo, Rome wasn't built in one day. Anyways, as long as the card has the correct drivers for vista (which most should) it should work with Vista. Nvidia is generally much better at drivers, than ATi. With the DX-10 card you only give up DX-10 capability. Since future games will be DX-10 and DX-9 your ok for gaming for a while too, it will be a while before it goes all out DX-10.
Personally I am completing my new build and went with a DX-9 card, since it far out performed DX-10 counterparts pricewise. From what I have seen the mid range DX-10 cards won't be able to play upcoming DX-10 games with suitable play rates and enjoy the DX-10 affects.
You have an apple icon, yet you run Windows, irony.....