I empathise with your nvidia driver problems. It can be frustrating trying to diagnose the cause of failure. I found a recent
thread concerning a dual-head setup for a GeForce 9800 GTX. In addition to this, have a look at genesis2seven's advice in this ubuntu
thread.
It might also be worth posting your install problem to this
NVIDIA Linux Forum.
Don't give up. Googling around yields lots of links on this topic with apparently successful outcomes. I often find taking a break before trying again, rests the mind and restores the mental stamina required to succeed.