Computers: Hyperthreading VS Duo Core and Quad Core

If you are in the market for a new computer, you may have heard the terms:  

hyperthreading 
core solo
core 2 solo    > duo core, with one core disabled
duo core    > two core
core duo
dual core
core 2 quad
core 2 extreme
quad core
core i3
core i5   > Similar to core i7,  introduced in 2009 
core i7   > Top of the line of the core, introduced in 2008/2009

These terms are all specific to Intel Computers.