Applications which have been designed to take advantage of mult-core processors will run about twice as fast on a quad core processor as compared to a dual core processor.
In terms of performance, The Intel Core i5 out-performs the Intel Core 2 Duo. So if you have the money, go for the i5.
core
The Intel Core 2 Extreme is a mobile processor for items like laptops, netbooks, and smart phones. It is a high performance processor that is featured in many products.
The Intel Core 2 Extreme QX6700 processor has high performance with multitasking and with most multi-threaded applications so it is much faster than other processors.
Intel Core Processor family
Both. The Intel Core Duo was a 32-bit dual-core processor. The Intel Core 2 Duo is a 64-bit processor.
Intel celeron is the lowest processor Intel offers. Below is the list from best to worst: Intel core i7 Intel core i5 Intel core 2 quad Intel core 2 duo Intel core 2 solo Intel pentium Intel celeron For laptops: Intel core i7 Intel core 2 extreme Intel core 2 quad Intel core 2 duo Intel centrino Intel pentium Intel celeron
80 core processor
The question you're asking, unfortunately, is not worded correctly. An Intel processor is a family of processor, where a quad-core processor is a type of processor. The Intel family includes many types of quad-core processors. However, to try and disambiguate what you're asking, an Intel core processor will be good, no matter what type it is. An Intel quad-core processor - for example, the Intel i7 - will perform fantastically well. The other main type of processor manufacturer - AMD - also have quad-core processors. However, a lot of it is down to opinion and machine build as to whether Intel is better than AMD, but personally, I believe Intel will out-perform and out-last an AMD processor.
Short answer: NO. Long answer: The Intel Atom processor is a very low-power, low-performance processor intended for netbooks that don't run processor-intensive programs. AutoCAD is one of the most processor-heavy programs on the planet, with even some dual-core processors suffering severe performance lag. For AutoCAD, I would recommend at least a high-end dual-core (upwards of a 2.6 GHz clock speed), like the Intel Core i3 or AMD Athlon II X2.
The best processor by Intel now is Core i7 975 Extreme Edition.
A variant when it comes to processors refers to related models of processors. For example, a variant of the Intel Core i3 processor is the Intel Core i5 processor.