Windows Vista and dual-core and multiple processors

All of the versions of Windows Vista down to Home Basic, support multicore (dual-core/quad-core) processors, and the Business, Enterprise, and Ultimate Editions all support multiple processors on the motherboard (that is, the motherboard must have more than one processor socket).
Exploiting Multi-Core Processors in Windows Vista -
http://developer.amd.com/documentation/articles/Pages/282007123.aspx
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Each of the AMD Athlon 64 X2 dual-core chips can be installed in the standard Socket 939 motherboards used by the latest Athlon 64 and Athlon 64 FX processors as long as the motherboard maker provides an updated BIOS. However, Intel's dual-core desktop Pentium D processors require a new motherboard based on the nForce4 Intel Edition, 955X or 945 chipsets, because of minor pinout changes in their design that require a new processor socket.
Note that a licence for Windows XP (or any other version of Windows) only allows the use of a single processor. If you use two separate processors on a motherboard, you have to purchase two licences for Windows. This is not the case with a dual-core processor, because it is installed as a single unit in a single socket on the motherboard.
The software that can make optimal use of a dual-core processor has to be multithreaded. Currently, there isn't much such software in existence. Since most software is still designed to make use of a single processor, a dual-core processor, such as the AMD Athlon X2 4800+, performs much like a single-core Athlon 64 4000+ processor when running an application, because both cores run at 2.4GHz, which is the same speed as the Athlon 64 4000+ processor. However, when two applications are run at the same time, each one is run on a core of its own, so both of them run at full speed.
Visit this page - http://multicore.amd.com/ - to find out more about AMD's dual-core processors.
HT stands for HyperThreading. It is technology that belongs to Intel that allows a single processor to emulate two processors, so AMD Athlon processors don't use it.
If you see nm in relation to processors, it stands for nanometres, and describes how small the manufacturing process - called fabrication - can wire the processor's interconnections - measured in nanometres. Intel has already updated from using 130nm to using a 90nm fabrication process, which is used to manufacture the Pentium 4 Prescott and AMD's Athlon 64 processors. Determined to keep one step ahead of AMD, Intel will soon be moving to the even more miniaturised 65nm technology.
A nanometre is a billionth of a metre (a nanosecond is a billionth of a second), where a billion is 1,000 million, so a namometre is 10 to the power of minus 9 of a metre; an incredibly small distance.
Below are images showing the top (left), and underside views of the Intel's Celeron 1.7GHz Socket 478 processor. The 478 is derived from the number of pins on the processor - 478 - that fit into the socket. Note that Socket 478 has been replaced by Socket LGA775.
The pins can clearly be seen in the image on the right. The processor can stand on its pins, but should one break off, or bend so that it doesn't fit into its corresponding hole in the processor socket, the processor won't be able to function. Bent pins can be straightened, but if a pin breaks off, a new processor would be required.
The start-up screen for a system running an American Megatrends (AMI) BIOS and an AMD Athlon 64 3200+ processor is shown below. The Checking NVRAM.. 1048576KB OK is 1GB of RAM. There may be power problems with upgrading a system to run large amounts of RAM. See the RAM page on this site for more information on this subject.
The system's DRAM clock is shown as 400MHz, so DDR400 (PC3200) RAM) is installed. Pressing the DEL key enters the BIOS setup program, pressing the F11 key brings up the Boot Menu, and pressing the F10 key runs the BIOS recovery utility, which you would use if the computer won't boot past the start-up screen, and you can't enter the BIOS because it has become corrupt.