By official work, do you mean office work?
Any of those CPUs are fine for word processing, but if you need things to do presentations, and do "multimedia" (is this 1080p video playback, DVD quality playback etc? do you need HMDI out, or is VGA out all you need?) then you need to be a little more specific. Laptop specs other than CPU are also important. I know Windows 7 64bit will work on those. Why are you comparing a CPU from 2007 and 2010? The newer one (P6200) will pretty much do better than the other two given it is 32nm, the others are 65nm (and it is also clocked higher). 65nm is old at this point, but I am sure still works.
TL;DR? What are the other specs of the laptop?