Is it pretty much open road or do you have a lot of intersections where you have to stop/slow down? The reason I ask is that unless you've got some decent sized stretches where you can just put your head down and go, you're not going to get to and from work much faster, - if that's the goal.
That being said, streets aren't really the RockHopper's element. A road bike will be more fun (IMO) in those areas where you can open it up, - even if it doesn't make that much difference in overall travel time.
A Bianchi Volpe might fit your price criteria. It's another cyclocross bike. Note: Cyclocross bikes typically come with cyclocross tires. If speed is a concern, factor replacing those into the cost of the purchase. A good set of road tires with decent flat protection won't be real cheap. Otherwise, there are quite few choices for pure road bikes at 1,200 or less. Just try a bunch and see what you like.
Edit: When you've got your options narrowed down to a couple bikes, do a search on roadbikereview.com or other cycling review site to see what people say about the stock tires for each bike. Often times the stock tires on road bikes ride nice but are flat prone. You may need to replace them right away. Factor that into the cost so you're not surprised later.
Last edited by tjspiel; 06-08-11 at 12:16 PM.