PC Hard Drives

They're not terrible exciting things to look at, but they can and will hold data. Hard Drives sole aim in life is to be like a faithful retriever, they sit waiting to serve on command.
IDE Hard Drives
IDE Hard Drives tend to have 2 speeds either 5,400 RPM or the more usual for today 7,200 RPM, this just lets you know how fast you can access data on the Hard Drive. naturally 7,200 is going to be quicker then 5,400 in practical terms however unless your authoring video footage, you wont see any great speed difference in day to day use.
Serial ATA (SATA) Hard Drives
Now if its speed your after and you PC will support SATA I or II then you should go for this. With access speeds of up to 10, 000 RPM and data transfer of up to 3GB/ second.
Back to Hard Drives in general. Happily unlike Golden Retrievers they don't dribble on your knee. As for storage, they range from 80GB (Gigabyte) to about 500GB, and getting bigger all the time.