To unmount the share drive (/mnt/win) just type
as root in terminal. You can type
to view your current mount point in your linux box. Remember that your XP share mount point that you just mounted will dismount once you reboot your VL system. To permenantly add your windows share to your linux is to add the command to /etc/fstab. You can search through it via google cause I seldom do that.
I think you have setup samba in your VL system. To view your VL share in windows, just go to start -> run, type //yourvlhostname or //xxx.xxx.xxx.xxx (your VL IP). Just do it just like you open other windows share folder.