The Toshiba MK2018GAP is a 20GB 2.5" hard drive which spins at 4200RPM and can be replaced by any similar drive. 4200RPM had been the standard speed on laptop drives for a long time but faster drives are now available and could be used. Laptop hard drives are usually fitted inside a frame that is specific to the laptop but the drive inside the frame is a standard size 2.5" drive. The faulty drive can be removed from this frame and a new one fitted in its place.
I would expect the recovery CDs to recover to any new hard drive but if you fit one with a larger capacity and run into problems then you could always start again and create a 20GB partition to recover to. You can then partition and format the remainder of the drive in Windows and use it as a data drive.
On some PCs there is a hidden partition on the hard drive but I think that this is unlikely as you have a set of 3 CDs for recovery. The information on this website seems to support this click here.