Two computers are better than one
My advice is to get an iMac and pick up a refurbished macbook if you need portability. For two reasons:
1) Convenience. Plugging and unplugging cords is a major hassle. I love knowing my iMac is waiting on my desk at all times with the cables for all my devices already plugged in (camera, video camera, printer, external drive, ipod, iphone)
2) Redundancy. If one system dies, you have an extra to use while it's being repaired. Plus it's amazing how often both computers get used at once when friends/children/relatives are around.
Cost is probably about the same when you consider that you would probably not only want a Cinema Display, but also a second power adapter and wireless keyboard and mouse. Most software publishers (even Adobe) allow you to install on both a laptop and desktop so long as there is only one primary user for both machines.
. As long as you don't game and don't do any GPU intensive work it'll be great. However, the macbook can only support up to 23/24 inch screen while the mbp can do 30 inch. What do you want to use your computer for?
