To have the system mount it rather than HAL (which is doing the per-user mounting) you will want to add the drive to /etc/fstab, which controls which filesystems will be mounted manually.
You would add a line like this:
Code:
/dev/sda1 /mnt/External vfat auto,user,rw 0 0
You might need to change the device node to reflect your system, and make the mountpoint valid, but that is the general concept. It would mount the device /dev/sda1 to /mnt/External using the FAT32 filesystem. Samba would then be able to access it regardless of the user logged in.
You will need to play with the mountpoint permissions to enable you and your wife to access it too.