A partition is a prepared part of the hard drive. On branded pcs and notebooks, often there is a hidden partition which has the files to restore the pc/laptop to its original factory state. Often this is called the recovery partition and is accessed by hitting an F key such as F12 when the machine first starts.

Have a look at Toshiba support here Click on the user guide tab and see how to restore it to factory condition.

Assuming you get XP on this laptop, you will need to max out the ram to 192mb... but it is going to be so slow as to be useless with a PII 366 processor. You would be wayyy better of putting 98se on it... or possibly windows 2000, but not XP.