In my case I wanted a bit snappier response when I start up an application, so I went to a newer operating system (generally a move in the wrong direction!) and light-weight windows manager.
For me it's mostly e-mail, browsing, and letters to legislators. And photo and audio processing, and... and... and...
Would be nice if I could get Adobe Flash to run. But not there yet.
Other family members are always finding more things they want the computer to do!