hyper-threading: performance boost or not?

I remember seeing - but now can't find - a thread discussion hyper-threading & turbo-mode on the intel i7 chips. My recollection of this post was that one or both of these things affected multi-boxing performance negatively because they were designed for situations when there was a single program running and in essence turned off certain parts of the core to bolster certain other parts. Because multi-boxing has multiple copies of the same program all demanding resources simultaneously, the disabled core capabilities loss outweighed the performance enhancements.

Can anyone say for certain whether any of the above recollections are true, specifically when talking about lower clock speed i7 chips, i.e. i7 Q720 @ 1.6GHz in an Alienware laptop? Would I be better off having ISboxer only using the "real" cores (odd numbered ones I believe) or is that all a load of horse puckey?

With an:
i7 920
Asus P6T Motherboard
GTX 275 Video
12GB 1600mhz DDR3
Patriot 64GB SSD
Vista 64-bit

I have all four physical cores set to all five of my warcraft clients.
Basically let Windows decide which core is needed for which game.

When I assign all of the logical cores to all games (in addition to the physical cores), the performance consistently drops by a very small amount.

My personal experience suggests, setting all the physical cores to each copy of the game, but not setting the logical cores to anything, results in the highest performance.

http://news.cnet.com/8301-13512_3-10362882-23.html

Non-authoritative source but it jives with the other stuff I've read.

Probably beating a dead horse here, but...

1) Hyper-threading does not help gaming (or boxing) at all. In fact, it can hinder it slightly

2) Turbo-boost is mainly helpful for when you're running one single-threaded app, But it is not detrimental to gaming or boxing. The general idea is that the fewer cores you are using, the faster the boost.