If you're in your late 20s (and a computer nerd), you probably grew up with DOS: CD, DIR, etc.

Besides, if you're a programmer on Windows, even if you're really young and started with .NET, I'm pretty sure the API and the MSDN docs still consistently use "directory" throughout.

See, eg:

http://msdn.microsoft.com/en-us/library/system.io.directory....