Without considering price and availability hereís what you need in a computer system.

First: you need a computer that is fast enough, to do what it needs to do, without impeeding your thought and work process.
Second: you need a computer system that will let you change software quickly without needing to learn a whole lot of new skills.  
Third: you need a computer that never needs maintenance. Perhaps you can upgrade its system now and then, but the hardware has to be reliable.  
Fourth: You need a computer that is fun. It must not only work, but must have good style in its way of doing things and have aesthetically pleasing images on the screen to be harmonious with your work.
Fifth: you need a computer that can do many things without difficult transistions from one task to another. You need to be able to pick up e-mail, finish a letter, check on the stock market, enter some names and numbers in your contact manager and never miss a beat. Those tasks should happen so quickly that you donít even think about what is happening.