Assuming we're talking SATA here (I wouldn't recommend buying IDE anymore unless you have no other options) then the physical installation is simple, cable it up and you're away. Once the machine has booted though Windows won't show the drive in My Computer, you'll need to create and format a partition on it in the Disk Managment control panel applet. That's pretty easy, it's all point and click stuff and pretty quick too if you remember to ask for a quick format.