Hello.
First thing you need to do is find out what your 40GB hard drive is set up to be. For example Primary Master or Slave etc.... once you find out what it is follow these steps.
1. Login as root.
2. Make a directory to mount the 40GB hdd to (mkdir /mnt/hdd)
3. Mount you hard drive (mount /dev/hdxx /mnt/hdd) (Here you change the 'hdxx' to your hard drive setup. For example if it was a Secondary Master 'hdc1').
You should now be able to view the info on the hdd by 'cd /mnt/hdd' or by using the gui to do it.
Just for your reference...
Primary Master = hda
Primary Slave = hdb
Secondary Master = hdc
Secondary Slave = hdd
and so on....
The numbers after the 'hda, hdb' etc, are the partition number. If you only have one big partition, just hda1 or hdd1 etc will do.
Good luck.
Craig