3.Optical Drive
If your laptop does not have a modular drive bay, replacement usually remains fairly simple, anyway: Often a single locking screw holds the drive in place; you just unscrew it, slide the old drive out, put in the new drive, and replace the screw. In addition, you may need to install any drivers that came with the new drive.
A replacement drive should be designed for use with your specific notebook, so buy one directly from the system's original manufacturer if possible. The advantages? For one thing, this ensures that you'll have the correct IDE channel settings (which often cannot be changed) for the drive; for another, attaching the faceplate to the drive can be difficult, and it's easy to break the faceplate when removing the original drive. Vendors put the eject button in different places, too, meaning that with the wrong drive you won't be able to use the faceplate at all.
In many instances a new optical drive will work without additional tweaking. If yours doesn't work, however, download the appropriate driver; you may have to search on the full model number of the part if you didn't obtain the drive from your notebook's vendor.