MBA original still working but showing its age: now mainly use for PowerPoint shows at the school where I teach. It is heading for retirement.
MBA rev B is my main teaching and research machine. Keep it in my teaching bag so I can grab and go when I have class. Well used but works great.
New version MBA 11 2/128 is my business and travel machine for non-academic work. Run Office, Omnifocus, financial software, Tinderbox, Devonthink, etc all at once. Have two book manuscripts on it, tons of case files, other business stuff. This one lives in my business briefcase and has traveled the world.
MBP 15, couple of years old, is my sort of desktop.
I'd be lost without Dropbox and Evernote.