OpenSSH

We’ve long been a proponent of OpenSSH.

You can grab a client/server version for Windows from sourceforge:
http://sshwindows.sourceforge.net/

However, here’s an interesting note about the SFTP server part of the package:

Creating Home Directories for you[r] Users
In the passwd file, you will notice that the user’s home directory is set as /home/username, with username being the name of the account. In the default install, the /home directory is set to the default profile directory for all users. This is usually c:\documents and settings.
If you want to change this location you will need to edit the passwd file. The passwd file is in plain text and can be edited in Notepad or any text editor. The last two entries for each user are safe to edit by hand. The second to last entry (/home/username) can be replaced with any other directory to act as that user’s home directory. It’s worth noting that when you run SSH on windows, you are actually running SSH in a scaled down version of cygwin, which is a Unix emulator for Windows. So, if you will be placing the user somewhere outside the default directory for their Windows profile, you will need to use the cygdrive notation.
To access any folder on any drive letter, add /cygdrive/DRIVELETTER/ at the beginning of the folder path. As an example, to access the winnt\system32 directory on the *c:* drive you would use the path:
*/cygdrive/c/winnt/system32*

Emphasis added.

http://www.digitalmediaminute.com/article/1487/setting-up-a-sftp-server-on-windows