disk drive is where all information is stored in a PC (except for BIOS
settings. More on that latter). A hard disk drive is a
magnetic storage device. Even though the disks, called platters, look
like CD's used in a CD-ROM, they are not the same.
for a hard drive you must consider not only the size of the drive (in
gigabytes) but also it's speed in RPM's. Along with the interface
type, these determine the access time and transfer rate for the data on
the hard drive.
You motherboard will normally have a build in hard
drive controller. If this one isn't good enough for, don't worry, it
can usually be upgraded with an "add-on" card. When upgrading, make
sure your ribbon cable is up to spec!
ATA 100 is the most common
interface type with home PC's. The interface type is another factor
in the overall picture of how "fast" your hard drive will be.
These, like most PC parts, just keep getting
smaller. The typical notebook hard disk drive is about the size of a
pack of cigarettes!