Open it and find out.
Shouldn't be much of a problem if you have assembled a pc before. When you find the harddisk, you can search for a serial number/production name, and then you can search via google for the datasheet, in wich is stated what kind of harddisk it is. (but I think you'll be able to find that out yourself at the moment you see the harddisk; I bet it's just a plain IDE harddisk).
-edit- and put the harddisk in a (linux) pc, so you can find out how it's formatted, and copy the system files from it.