i7 processor on Windows 7 PC

I'm looking at possibly upgrading from my i5 3350p 3.1 quad core processor to an i7 since I occasionally get messages that I'm running out of CPU power. (I'm set on 3 cores @ 99%). I have two questions: (1) Can I get some recommendations on an i7? (Once I sort thru them, I can choose one that's compatible with my mother board). (2) I've been told that most quad core processors actually have 8 cores. My computer guru says that's true only in hyperthread. Is hyperthread the same as turbo boost? If so, he tells me turning it off would mean the processor would only have four cores to work with again and I wouldn't gain much. True of false?

Jim