Q:

Can someone clear up the terms Core Duo CPU, Quad Core, Dual CPU, etc.?

I'll be buying a new computer in the next couple months and want to understand the dual/duo/two CPU issue:

Core Duo CPU (is this one "duo" CPU or two?
Quad Core (four cpus?)
Dual CPU (two cpus?)
2 CPUs (does this always mean two physical chips?)

I can look these up on Wiki, etc. but it's just an explosion of new terminology. What is the simplest way to understand this "two CPU" thing for someone who:

is a developer and wants to begin testing out e.g. threading issues on two CPUs
does not play video games
will be doing screencast recording (camtasia)
want the computer as fast as possible, e.g. 20 applications open, constantly downloading, streaming music, videos etc.

A:

Core Duo CPU = Intel's line of dual core processors. This means that there are two logical CPU's on a single chip.
Quad Core = Four logical cpu's on a single chip.
Dual CPU = two chips (normally with a single core, but you can do multiple chips of multiple cores as well)
2 CPUs = What it says, two CPU chips
The beauty of multiple processors or multiple cores on a single processor is the ability to perform multiple instructions at the same time in parallel instead of having to wait for one instruction to finish before starting another. This can make it much faster and efficient to perform CPU heavy tasks such as video editing, graphics, gaming, etc. You will only see performance benefits from applications that effectively utilize multithreading, otherwise it will NOT utilitize multiple cores/processors or at the most will rely on any built-in multithreading capabilities of the OS.
Multiple cores/processors can help with multitasking significantly, but you will still have to contend with other potential performance bottlenecks such as the amount of available RAM on your system. If you don't have enough RAM to run all of those processes, it is not going to matter a whole lot how many processors you are banging out instructions on.
http://en.wikipedia.org/wiki/Multi-core_%28computing%29

A:

Types of CPUs:

Single Core CPU - 1 chip, 1 Core
Dual Core CPU - 1 chip, 2 cores
Quad Core CPU - 1 chip, 4 cores

Motherboards:

Dual CPU - 2 chips, ? cores (depends on chips)

Other:

Core 2 Duo - Intel name-brand for dual core CPUs (see dual core above)

Examples:
A single core system has 1 chip with 1 core.
A dual CPU quad core system has 2 chips with 4 cores each.
A dual core system has 1 chip with 2 cores.

A "core" is a logical CPU contained in a physical chip.
For most situations, you're only going to need 2 CPUs (dual CPU) if you're running a server or you're on a dev machine testing out something that will run on a dual CPU machine. Otherwise, you're pretty much good to go with just a dual core chip; quad core if you're really going crazy.

