I have been using a 24 or 27 inch (forget which) iMac as my main desktop in my office at work. I recently plugged a 24 inch widescreen monitor into it to get a lot of screen space for preparing presentations. At home I use a 17 inch laptop with external keyboard and mouse and sometimes plug it into a 28 inch external monitor. Both work well. If you have the laptop the monitor addition is obviously cheaper.