But do dual processors cost the earth? No, not in comparison with a high performance single processor PC. The veritable Tom's hardware site has this article on a low end dual Xeon processor solution being faster than - and costing less then - a high end single processor solution.

We were the first to bring AMD's dual processor technology to the UK read review and have won many performance and innovation awards since then. While we don't know everything there is to know about dual processor systems we've put together answers to the dual processor questions we get asked most often. 

What version of Windows?

In response to what seems a very popular question here's the score on the OS: 

Windows 98, ME and XP Home do not work on dual processor systems. They will however run on Intel Pentium P4 computer systems with hyper-threading turned on as hyperthreading creates a "virtual" or "logical" second processor, not a physical one. Windows XP Pro (or Windows Vista) is what you need for a dual CPU computer i.e. where there are two physical processors. Note: Windows NT 4 and Windows 2000 Pro also work with dual processor systems, as of course does Windows 2003 server.

What programs does a dual processor run that a single processor doesn't?

Nothing. Generally speaking, all the programs that run on dual processor machines also run on single processor machines.

Will my software run faster if I have a dual processor PC?

Probably not. Yes, that's what we said. PC suppliers will be happier to charge you extra for a dual processor computer whether you are going to benefit from it or not. In fact they may not know that most programs run slightly slower on a dual processor computer.

So why buy a dual processor PC?

The advantage in having a dual processor PC is for programs that have been optimised for multi-processor operation. Programs like Adobe Premiere, other video editing and 3D packages etc. will generally benefit quite substantially. MS Office won't, neither will Outlook/Explorer. If you are unsure whether a particular software program will run any faster on a dual CPU system contact the manufacturer of the software and ask them.

What's the difference between a dual processor PC and a dual-core one?

Dual processor PCs have been around for a while and have been the backbone of the small server market, they contains two distinct physical processors. Dual-core is a more recent technology and involves two processors being effectively mounted on one die. More on dual-core. You can run a dual core machine on versions of Windows like XP Home but you do need XP Pro/Windows Vista/Windows 2003 etc to run a system with two physical processors.

How do I benchmark dual processor systems?

Benchmarking dual processor systems is tricky because benchmark programs are generally designed for testing single processor machines. Running such a benchmark on a dual CPU system will give you extremely misleading results. For example, one of the most used Benchmark programs, Sysmark, works by putting your PC through various typical office tasks and compiles the time it take to complete those tasks. Most of the programs it uses to run those tasks, like Word, Excel, Netscape etc are not multithreaded and are incapable of pushing both CPUs to work to their limit.

There are specialist server programs, other innovative ways you can test a dual processor system (by setting up four SETI threads, for example), and you can use third party benchmarking services... you can even load a copy of Linux and avail the testing programs available only for that platform.... but nothing in benchmarking in 100% accurate.