Explanation: (Difference between Intel Core i7 and Core 2 Duo) - The Core i7 is a completely new architecture which is much faster and more efficient than the Core 2 Duo. Currently only the Core i7 920, 945 and 965 XE versions are available. Of that the Core i7 920 is available at just $284 which makes it a great buy. It offers better performance than almost all Core 2 Duo processors. Native Quad Core, More Cache and Hyper Threading: All the Core i7 processors are Native Quad cores (4 cores), which means that they actually have 4 cores on a single die, while the older Core 2 Duo processors like the Q6600 (2? = 4 cores) had two cores on a single die, and two such dies merged together. This increases the processing speed greatly. They also have 256 KB L2 cache per core and a shared 8 MB L3 cache which has proven to be much better than any cache configuration in Core 2 Duo. It also has HyperThreading support which means that each of the 4 cores can process 2 threads simultaneously, so you get 8 virtual cores. This helps in running many applications parallely and also in gaming. Quick Path Interconnect (QPI) and On Die Memory Controller:

The Core i7 processors sport the new Quick Path Interconnect technology which replaces the FSB (Front Side Bus) to connect the various components in a computer. QPI is much faster than FSB and hence improves the overall performance. It is even faster than AMD’s similar HyperTransport 3. 0 standard. The Core i7 have an On Die Memory Controller which means that it can access memory much faster than the Core 2 Duo processors which had an external memory controller. Intel has borrowed this feature from AMD. All the four cores, memory controller, cache are on the same die which improves the speed and performance greatly.