The actual size of the drive should be 156.25gb.
You get this by 160/1024=0.15625*1000
and they were all command line using fdisk. I tried doing this in a command prompt and it wouldn't let me.
It won't let you because fdisk was done away with in WindowsXP. The command you want to use is format.

Partition it into sperate 32gb sections. If you don't windows will read a disk error and run chkdsk.