Hyper threading does have its advantages particularly with encoding. Encoding HD with Sony Vegas pushes my 2600 K to 95% across all eight "cores" (4 being physical cores.) There is also the occasional game such as Left 4 Dead 2 which seems to lean on the CPU far more intensely than the GPU with multi threading enabled in the game options.
when games use hyperthreaded cores, it general degrades performance.
if l4d2 is anything like l4d then: