You can make a user's home directory point directly to this windows location/share. What I would recommend doing is setting the web user's home directory to point to this network share you have set up in GA Services.
If this is the only place you'll ever need this web user's uploads to go, that will work fine. If you would like the user to upload some files to this directory, and other files to another directory, you could utilize virtual folders. That way, the default webdocs location can be used for other types of uploads or downloads.
That is merely a suggestion, in the event you needed additional folders for other tasks.