[Pictures] Finished Computer Build!

CPU/Proc/Processor/Core = Central Processing Unit- It is what makes your computer work. It does most of the work. Probably the most important part of your computer. Produced by Intel and AMD.
Mobo/board/ = Motherboard- It is the backbone of your computer. Everything is attached to it, and it supports all of your components. Produced by the Taiwanese
OS = Operating System- It is the interface of your computer. Without it allows you to tell your hardware what to do. Many types, most common are Windows, Mac OS X, and Linux.
RAM/memory = Random Access Memory- It is what stores what your computer is currently running. Whenever you close an application (or more accurately end a process) the RAM that was allocated for that application is cleared. It is also cleared every single time you turn off your computer.
GPU/graphics card/card = Graphics Processing Unit- The secondary processing unit. It helps the CPU process the graphics and when you're playing a game, it is the GPU that is drawing those frames. It can be either integrated or dedicated. Integrated GPUs have no RAM for themselves and have to use System RAM while dedicated GPUs have their own banks of RAM that they access. As such, integrated GPUs are much weaker than dedicated GPUs.
HDD/HD = Hard Disk Drive- The permanent storage location. Unlike RAM, the information on the HDD is never cleared unless you clear it yourself. It uses disks called 'platters' to store information. The less platters there are, the faster the drive can access information because the HDD utilizes moving parts.
SSD/solid state = Solid State Drive- Newer form of memory storage. Like the HDD it is permanent storage, but unlike the HDD it doesn't use platters or moving parts. As such it is extremely fast when accessing data which allows you to open applications quickly.
PSU/power supply = Power Supply Unit- Device that supplies power to your computer. Comes with different rails of different voltages.
OCing = Overclocking- The act of pushing a part's performance past its designed usage. Most common to overclock CPU, GPU, and RAM to get higher speeds and better performance.
Xfire = ATi CrossFire- Using two ATi Graphics cards in tandem to gain extra performance. Two ATi graphics cards can be 'combined' to give the user better performance. There are limitations to CrossFire, and usually CrossFire works with two of the same cards for best performance. However it is possible to CrossFire different GPUs.
SLi = Nvidia SLi- Nvidia version of CrossFire. Same idea, except the GPUs must be the same.
FPS = Frames Per Second- Self explanatory name! It's how many frames your GPU can draw in a second at a given resolution. The higher the number, the smoother the 'motion' in the game will look. All games are actually just like slideshows with insane amounts of slides changed insanely quickly. The higher the resolution, the more your GPU has to draw, so that is why higher resolutions require better GPUs!