I would just like to thank m@riposa for his post, it has just worked great for me. I'm running Windows 7 on Snow Leoppard.
I set up a file in finder for shared files, then in settings for Vbox,before loading Windows, I used the drop down options to the file path for the file I created in finder.
The only problem I had was Windows 7 doesn't have a "run" box, in search type "command' and then clicking on it opens a terminal window in which you can type the instructions given by m@riposa.
If you type it right and get no errors, close the terminal window.
Open "my computer" in Windows and there will be your shared network location, for you to drop/take files from.
Thanks to all on here for such a fantastic resource of help and knowledge.