I can't get it to work either...
I've been messing with this for the last 2 or 3 hours and no matter what I do, I can't access the shared Windows folders from the Mac OS, I can't ping the Windows "PC" from the Mac, etc...I swear I must have turned every possible setting on and off and on again several times and ran every possible "wizard" I could find. No luck.
Is there some other way to copy files from the Mac to the Guest OS?