That's correct -- we should be able to do all of that for about $220/month with cPanel and 2x 200GB drives. We can also get everything set up just as you have it set up right now on your shared hosting packages. Everything will remain on the shared servers until you are satisfied with the sites on the dedicated server.
As for the difference between the dual 3GHz and the dual 2.8, it's going to be minimal in your case. I would definitely go with the 2.8's instead of the 3.0.
