Whatever program I'm using always goes on the 19". On my 15", I always have MSN and WinAmp running, as well as a folder open with all of my albums. If I'm talking to someone on MSN or loading up MP3s, I don't have to swtich or minimize windows at all - I just slide over to the left monitor and set it up. I can also have a video going on one of the monitors while working on the other. I'd obviously rather have two 19" monitors, but for everything I use the dual monitor set up for, the small 15" is perfect.