1600x1200 is too small for me, even though I use 4 virtual screens. But having a second monitor that's not the same size as the main one just gave me problems so I scrapped it. Although it was nice to have ICQ, IRC and the playlist always visible, as well as being able to utilize the entire screen when using Indesign/Photoshop since I could put the tool boxes on the extra monitor.
I've found a 24" flat widescreen monitor which looks really sweet, if I was rich I'd definately buy one. The 22" CRT monitor fills up the entire desk. =/ But it is nice to be able to run 1600x1200 at 104 Hz.