Holy cow, I wrote a book!
As a follow-up to
the difference between My Documents and Application Data,
I'd like to rant about all the subdirectories of My Documents
that programs create because they think they're so cool.
I'm sure there are more.
Everything in the My Documents folder
the user should be able to point to and say,
"I remember creating that file on such-and-such date when I did a 'Save'
from Program Q."
If it doesn't pass that test, then don't put it into My Documents.
Use Application Data.
And don't create subdirectories off of My Documents.
If the user wants to organize their documents into subdirectories,
that's their business.
You just ask them where they want their documents and let it go at that.
(Yes, I'm not a fan of My Music, My Videos, and My Pictures, either.)
Omar Shahine points out that
Apple has similar guidelines for the Macintosh.
I wonder how well people follow them.