Should a informational box for a wide form be centered, left or right aligned?

I am working on updating the layout and styles of our existing application. At the top of a very wide table that has lots of checkboxes and fields is a information box. We need to explain some basic information to the user.

The original information box is centered and 600px wide. It has a comfortable amount of text per line. However it looks very out of place compared to the rest of the design, I would rather it be anchored to the side or the whole width of the table.

The following image has the three possible layouts I am contemplating.

The first seems like too many words for each line. The second and third seem better. If someone has links to how other sites successfully execute instruction sections on the top of very wide forms would be the best resource for me.