Assuming you have a spare bay and IDE cable connector - go for standard drive size to suite
unsrall in bay connect power and data cable
re boot and there you are.
It will need to be formatted [what system are you?]
FDisk routine for DOS 95/98/ME- NTFS for 2000/XP
or if you arenot too sure about the techniques here
gor for a USB external -simply plug'n'pray