I had a chance to ride in a drag car simulator in Orlando, FL on spring break two years ago, man what a blast. 0-110 in right at 2.0 seconds. Anyways, I was told it was comparable speed to that of a top fuel drag car, so I guess I would like about 4500+ HP in my car just to I could wake up every day excited to go to work. Realistically speaking, I'm thinking right now that anything near 400 would be perfect, not so much that you can't stay out of trouble, but then plenty to really get you into trouble!
BTW... I thought I would add that the simulator was an actual moving car (two mod motor Mustang GT Bodies) powered by air. It was in an area called Old Town (or something like that) and right next to Disney. I would definitely recommend that place to anyone looking for a good time. They had a bike show the night I went as well, but I was told they alternate back and for car/bike once a week.