I agree,the smb server is the easiest way to do it....just look for this part in your xml file...
<bookmark>
<name>SMB</name>
<path>smb://DOMAIN;username:pwd@MyWindowsServer/movies/</path>
</bookmark>
</pictures>
Now you can do one of many ways to do this,depending if you use a password/username or whatever on your pc. where it says 'username' you put a username...etc etc. Make sure you label a folder on your pc for each of the setting that are going to be shared on your pc-to xbox. (music/pictures/videos/files) Once you have a folder on your pc set to share,then you link that folder to the part of the xml that you want to recognize it. Eg,you folder with all your pictures will be linked to the pictures section on your xml. Simple. One more thing,I've noticed that if you run a pc with a password and username,you have to be on that desktop on your pc for the xbox to find it for some reason. It might be just with my settings,but dont be surprised. <