The video card will not have any significant impact. For boot disk I would opt for a Velociraptor or - if you have money to burn - an SSD. For the rest look at my disk setup, as linked to in the PC Buying Guide at the end. It will show you my configuration. Maybe it will give you some ideas.
Personally I would opt for an i7-920 and overclock it to 3.6 GHz (faster than the i7-975) and invest the savings from not buying the i7-975, which is FOUR times as expensive, to improve the disk setup.