You would have to set up one or more shared folders - even the entire C drive - on your Windows 7 VM (the guest), and then access it/them from the Finder in the OS X host (via SMB); here are some interesting links:
http://macs.about.com/od/filesharing/ss/file-sharing-win7-snow-leopard.htm
http://www.sevenforums.com/tutorials/24232-sharing-permissions.html
http://www.youtube.com/watch?v=aW4jor40Pw0
Of course, all this is if you want to access the entire C drive or another shared folder while the Windows 7 VM is running.