I have two 20" 1600x1200 monitors and I stick to 80 columns because it lets me display multiple text editor windows side-by-side. Using the '6x13' font (the trad. xterm font) 80 columns take up 480 pixels plus the scrollbar and window borders. This allows one to have three windows of this type on a 1600x1200 monitor. On windows the Lucida Console font won't quite do this (the minimun usable size is 7 pixels wide) but a 1280x1024 monitor will display two columns and a 1920x1200 monitor such as an HP LP2465 will display 3. It will also leave a bit of room at the side for the various explorer, properties and other windows from Visual Studio.
Additionally very long lines of text are hard to read. For text the optimum is 66 characters. There is a point where excessively long identifiers start to be counterproductive because they make it hard to lay out code coherently. Good layout and indentation provides visual cues as to the code structure and some languages (Python comes to mind) use indentation explicitly for this.
However, The standard class libraries for Java and .Net tend to have a preponderance of very long identifiers so one cannot necessarily guarantee to be able to do this. In this case, laying out code with line-breaks still helps to make the structure explicit.
Note that you can get windows versions of '6x13' fonts Here.
