I thought you had a Core i7. Those only come in four cores and only one can be on a board. You'd need a four-core, dual-processor Xeon to get 8 cores.
"Hyperthreading" is the Intel brand name for simultaneous multithreading, a trick to make one processor core act like two for the OS. There is hardware on the core to help it juggle two threads and keep the pipeline filled. Depending on your application you can gain a bit of performance using this method, or actually lose performance. But it is nothing like having more real cores, especially in cache-intensive applications.
Don't worry, I have seen this confusion before. But only in amateurs.
. It's a Mac Pro Killer, anyways.
A high-end i7 based machine will never get close to a high-end Mac Pro, which is based on the Xeon processor, so it can have double the total cores, double the total cache, and double the memory channels per chip. One's desktop class, one's workstation class, there's just no competition. However, a high-end i7 will beat a single-processor low-end Mac Pro.
Do you make this stuff up as you go? As far as I know they are triple channel memory controllers, just like the desktop variant. I've seen amateurs make mistakes like this before.