Oops. I forgot the Linux part of this post.
In my Linux guest OS (Fedora 8), I changed two files to get NAT file sharing to work.
Added host computer name to /etc/hosts:
Added folder shares to /etc/fstab to auto-mount:
//czflmc1/C$ /mnt/C cifs auto,rw,user=dude,pass=x,uid=500,gid=500 0 0
//czflmc1/D$ /mnt/D cifs auto,rw,user=dude,pass=x,uid=500,gid=500 0 0
Works like a charm! YMMV... (Your Mileage May Vary)
P.S. I had to create the /mnt/C and /mnt/D directories as root first.