One of the most frustrating things that can happen when your building a computer system is to try to plug a cable in, and find out that the cable you have is too short. It stops you dead in your tracks. Pow. Go on-line and order a longer cable. What a pain, plus extra shipping charges, and will the cable you order be long enough? Let's stop and measure. Maybe Radio Shack has it, jump in the car, nope. You get the idea.
The most common problem you'll have is the cable is too short. Most of the manufacturers that provide cables with their components always provide short cables. They want to keep their costs down and still provide their customers with everything they need. The result, short cables.
What I propose is for you to have a couple of extra longer cables, so that this won't slow you down. What cables should you have in your kit?
DVD's hook to the motherboard either with an IDE cable, or the newer DVD drives use SATA cables. The IDE cable is usually an 18" ribbon cable. The ribbon cable is relatively wide, and stiff. It get's in the way of hooking up other cables and impedes air flow. If you have a full tower and put the DVD in the upper slot, there's a good chance the 18" cable will not fit.
I prefer the round IDE cables. Better air flow, not as stiff and easier to route in the case. So the first cable you should get is a 36" round, not flat, IDE cable, $4.99.
Next SATA cables, SATA cables are used to hook up hard drives, and maybe your DVD drives. Same sceanario SATA cables are too short, let's get a couple of extra longer SATA cables. Two 39" SATA cables, $1.99 each, or $3.98.
At this time, I'm not going to cover audio or video cables. They depend on your components, the ports you have available, the distances between components, and what functionality you want to achieve. We'll leave these to later.
Current motherboards usually give you over four USB ports. You can get USB externder cables to increase your cable distance, and USB hubs which allow you to hook more than one USB device to a single port.
RJ45 Ethernet cables, these are the cables you'll use to hook computers to the network, to the Internet, and to hook to other computers. There are two types of Ethernet cables. Regular RJ45 cables that you hook from your router to your computer. I recommend you get a 50 foot cable, 50 feet? Yes, that way you can string a cable from the network, to your computer no matter where it is in the room. I found a long ethernet cable is invaluable. Friends come over with laptops and their computers, and you want to get them connected to the Internet. It's a lot easier to string cable that move hardware. The cable runs $6.99.
The other type of Ethernet cable is called a "Crossover" cable. This is a cable that switches the wires inside the cable so you can plug two computers together, and have them talk to each other, which gives you an instant, high-speed network. Ethernet cables are normally color coded with crossover cables being orange, and normal cables being light blue. A 50 feet crossover cable runs $8.39. You can also get a Crossover Adapter Plug for $13.99 and skip the orange cable.