There are probably less than two dozen songs I listen to in any given week. A player that holds 100 songs is just fine for me. When I tire of those songs, I will simply load new ones.
That sounds right, but then most people don't drive 100 mph but they like to have cars that are capable of going that fast. Most car speedometers even show 120 or more on the dash.
I know a half dozen people who have two or three thousand songs on their iPods/desktops. Most of those I know with iPods have something over 1,000, and a good percentage have entire operas or symphonies on the device -- though I don't know the opera to song ratio.
The genius of the iPod and similar devices is that it is possible for people to carry all of their music with them in as little space as a shirt pocket and can put away the clutter of the cd cases.
I guess it all depends on the individual's use for the device. For you, something like the iPod Shuffle would be great. For others, the Nano, and for others still, the iPod is ideal. Fortunately, the market supports all these great little devices for all of us.