I looked at this question: http://stackoverflow.com/questions/310117/ignoring-folders-in-mercurial that mentions how to ignore a folder, but that's not what I need.
I'm using TortoiseHG and after I "add" all my folders, they show still as "?" instead of "+". The files within them show "+", but the folders themselves just show "?". Is this a problem with Mercurial on Windows XP? Or, is it a problem between my keyboard and my chair?
Mercurial adds only files in, and infers the folders from the actual file names. If you drop down to a command line and do hg status, you will see that folders are not listed at all. The files within the folder you added will be listed with the A tag, but the actual folders don't list in a hg status command.
You don't need to add the folders separately (in fact, Mercurial doesn't handle plain folders/directories at all). As long as your files are there, you're fine.