It is hard to give a definitive answer, but the three most common are the CPU, RAM, and Video Card.
RAM and Video Card may be more popular as they are significantly easier to replace in a desktop.
RAM is all that can usually be upgraded in a laptop.
So, i'd say deductively RAM.
The CPU
hard drive
The most popular PC game is World of War Craft.
There is no agreement upon what the most popular pc shooter game is, for it is all opinion. However, the most popular answer to that question seems to be Call of Duty.
EverQuest II: The Shadow Odyssey for PC is one of the most popular RPG around.
PC Magazine, PC World and Family PC are among the top ten most popular PC magazines in the US. Others are: PC Advisor, PC Gamer, PC and Tech Authority, Wired, Laptop, Maximum PC and PC Computing.
The newest CPUs and video systems generate the most heat.
mac or PC
Hard disk drive.
Motherboard connects every component of a computer and so its AKA "backbone of PC"
A component located inside the computer chassis / case.
Most TVs can be used as a computer screen. Especially if they have VGA connectors on the back. However, if your TV lacks this type of connection you may be able to connect using component or HDMI cables if your computer supports this. You can always upgrade the PC's video card to get this functionality.