Building a laptop is a little different from building a desktop computer. With desktops, virtually everything is customizable, with lots of options for every component. Laptops, on the other hand, require a "barebones laptop" to start. Essentially, this is a prebuilt laptop with parts that can be easily swapped out for different ones. While not as customizable as a desktop, building a laptop does involve a fair amount of DIY work.
The barebones laptop, also called a "laptop case," comes with a motherboard and an optical drive that probably can't be changed. It also includes other typical laptop components like a CPU, hard drive and memory, but these can be changed quite easily.
The central processing unit (CPU), or processor, is the brain of the computer. Purchase a CPU that is compatible with your barebones laptop.
The video card processes all of the graphics displayed on the screen. The better the video card, the smoother the graphics flow. Again, purchase one that is compatible with the barebones laptop and the motherboard.
Random access memory (RAM) stores stores data not currently being used but that will be needed soon. The more RAM you have, the more tasks your computer will be able to perform at once. There are three major types: SDRAM, DDR-SDRAM and RDRAM. Verify that your motherboard supports the type of RAM that you want.
The hard drive stores all of your data (documents, music, pictures, etc.). The bigger the hard drive, the more you can fit on it. A 160-GB hard drive should be adequate for most users.
Wireless cards allow you to connect to wireless routers and access the Internet. The current standard for wireless connectivity range and speed is 802.11g. The 802.11n cards are faster, but to utilize the added benefits, you must connect to an 802.11n equipped router. Most Wi-Fi hotspots use 802.11g connections. Wireless cards come with either Mini PCI or Mini PCIe slots. Verify which one your motherboard uses before purchasing one.