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I am confused about the fact that the new computers with Intel Core Duo seem to have less speed than my present computer which is over two years old and has 3.4GB Intel. If a computer is quoted as Intel Core Duo 2.66 does that mean because it's a duo processor you double the speed to 5.32GB?
No, not exactly, what you get is the equivalent processing power of 2 x 2.66ghz processors. So any programs that know how to use two processors at the same time become screamingly fast, whereas those programs that don't run at normal speed.
A decent simplified article a little out of date:
http://icrontic.com/articles/dual_core
As a comparison, I went from a 2.8GHz P4 to a Core Duo 1.8GHz (that's the original Core, the current Core2 has more performance for same clock speed). It's noticeably faster than the 2.8GHz P4.
The article CCT linked to is quite good.
Basically there are 3 ways to increase a processor's performance:
Clock speed - simple, instructions execute faster, it's faster. But it's not as simple as it sounds, there are complications.
Execution efficiency - this is the complication. Sorting out the things that stop a CPU from achieving the potential from its clock speed. Caching, pipelining, branch prediction/prefetch, data transfer...
Parallel processing - more than one execution unit means more instructions are executed in a given time, therefore it's faster.
The P4, due to design decisions at Intel, utilised the high clock speed philosophy, but its execution efficiency was not very high. Core uses lower clock speeds but has higher execution efficiency, so even the Core Solo CPUs give relatively good performance. But of course Duo gives much more punch in many applications (including just the running of Windows itself, or another modern OS).
Thank you everyone for the explanations and links.
I could add Memory RAM to ways of increasing computer speed.
Platypus touched on this a little...
There are many aspects to how processors can be designed, the p4 family was made to reach high clock speed, but not very efficient (hyperthreading was developed to bypass this shortcomming). For the size of the die, the p4 reached unheard of gigahertz speeds.
AMD started a subtle but effective campaign, "It's not the speed that counts, it's how much overall work it can get done". AMD made some amazing processors at that time.
Core2 series takes that page from AMD, they have designed a very efficent processor and are using the reduction in die process to get ever more increases in hertz.
a core2duo at 2.4 will beat the pants off a dual p4 3.2 system.