Hyperthreading question

http://en.wikipedia.org/wiki/Hyper_threading
For each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible. The main function of hyper-threading is to decrease the number of dependent instructions on the pipeline. It takes advantage of superscalar architecture (multiple instructions operating on separate data in parallel). They appear to the OS as two processors, thus the OS can schedule two processes at once. In addition two or more processes can use the same resources. If one process fails then the resources can be readily re-allocated.

Hyper-threading works by duplicating certain sections of the processor—those that store the architectural state—but not duplicating the main execution resources. This allows a hyper-threading processor to appear as the usual "physical" processor and an extra "logical" processor to the host operating system (legacy operating systems see two "physical" processors), allowing the operating system to schedule two threads or processes simultaneously and appropriately. When execution resources would not be used by the current task in a processor without hyper-threading, and especially when the processor is stalled, a hyper-threading equipped processor can use those execution resources to execute another scheduled task. (The processor may stall due to a cache miss, branch misprediction, or data dependency.)
This technology is transparent to operating systems and programs. The minimum that is required to take advantage of hyper-threading is symmetric multiprocessing (SMP) support in the operating system, as the logical processors appear as standard separate processors.

nice answer from groundrat, thanks  

awesome. thanks. but, to keep it nice and simple, if i'm playing a single threaded game that's maxing out 1 thread on the core, would any other load from background tasks slow down my game? say the second thread is at 5% load. that means the game is really only getting 95% and the other background program is getting 5%. am i correct?

Okay. I got it now. Thanks for clearing it up. Now I can sleep at night and think about something else in the shower.    

Best answer selected by marshal11.