I used flashftp to create a new folder in the xbmp folder for music and such. You should then be able to read this new folder from xbmp. There is a newer version of xbmc. Also you can set it up to access files directly from your PC. Search the xbox-scene tutorials for this feature. This way you don't have to save the files on the xbox hd. It will also play movies this way too.
You will have to edit the xbox media .xml file. This file has a section called movies, here you will need to edit the file to show E:\..foldername... For eg: I have my movies stored in F:\Movies so in the xml file I have edited the movie section to look in F:\Movies
