Thanks for all the responses guys. I appreciate it. Seems that my negative is the major problem, and I'm going to try to be more conscious of this on this upcoming Monday.
I'm not really sure why my lockout strength seems so much better than my strength off of the floor. It could be the fact that when i used to pull with a rounded back, i developed a lot of strength at the top of the lift, but never really developed the strength needed for the bottom portion of an arched (or neutral-spined) deadlift. Strange reasoning, I know.
In the past I have also done a lot of Rack Pulls, Pull Throughs, and Speed Pulls.
About the rolling of the bar- I've been experimenting with this recently, as it seems to help me pull myself into the starting position. It also helps me to feel the weight on my heels, for the start of the pull.