Most computers these days come with a single processor. In the good old bad days, a processor was judged by clock speed. The two major processor companies were AMD and Intel. Intel most obviously pumped out the higher clock speeds but many people claimed that AMD had a superior chip architecture.
Higher clock speeds may generate more power but at the same time they also increase the amount of heat. It also did not alleviate the strain of something known as bottle necking where even with an uber fast processor, there were limits to what could be handled.
AMD did something bad ass. They busted out what is known as a dual core processor (2 processor's for those who don't have a grasp on the English language and the meaning fo the word dual). What was discovered was having two separate processors to handle the many tasks that a computer has was far superior to the old uber power system. This of course was a blow to Intel's e-peen so they had to have one to and they do.
A dumbed down example of a how a dual core is helpful for normal computer users is the good old fashion example of running an anti virus while listening to music. Both can function to their full capacities without interfering with one another. This for the most part is a good example.
The quad core processor (with the ability to upgrade to 8 if I heard that video properly) is 4 processors (more or less). This allows for more functionality at the same time. Which was explained in the video. The guy was after all playing a game, decoding DVD's and a few other things.
Quad graphics cards. Something a few months ago became very popular. It was called dual sli I believe. In short, two graphics cards. When one renders 3D graphics or plays a video game without a graphics card. Your computers uses your system memory to load up the graphics. Needless to say, this leaves less memory for the rest of the functions required. A common side effect is what is known as lag. Lag is offered referred to an internet connection but can be universally applied to a slow and jerky game movement. When one uses a good graphics card, things roll smoothely. 2 SLi cards are basically 2 good cards connected and using their own memory together for better functionality. Add another 2 cards and you can greatly increase the graphics and rendering performance of any game (I'd love to see Oblivion MAXED out without lag). Gamers and designers need a good card. Having 2 or 4 make things a lot nicer.
Another thing to note about graphics cards is the number of VGA/DVI/S-Video connections you can have. For simple purposes, the 5 monitors for one computer. Last night I did that with my Samsung 931BF and my 23" Samsung HD TV. On the television I was watching movies while on the monitor I had all my chat programs open. Very sexy.
Memory. Most folks know this as basically what's used to load up your programs and how quickly. The more the merrier. Industry official standard is 512mb. Gamer standard is a minimum of 1gig. With the near upcoming public release of Vista. The industry standard will rise to 1gig and most gamers will move on to 2gigs. 4 is excessively hot... I don't mean hot as in temperature but hot as in sexy as hell.
This is by no means technical and in my dumbing it down I may have made mistakes. I'm not a professional in this field but I do enjoy tinkering. If anyone is more technically inclined and cares to point out any errors, I would appreciate it.