There is not a single game on the marked that benefits from Hyper Threading.
So yes, for gaming you can disable it, but i am not sure if disabling it will boost your 4 cores performance.
That's not true. While most games do not, there are a few games that do benefit. Resident Evil 5 gains 10% more FPS with HT, same with Metro 2033. BF3 also benefits from HT in multiplayer. More games are starting to see a gain with HT or more than 4 cores, but there still isn't a lot.
Giving the pain it is to disable and enable it, I'd leave it enabled because when you do benefit from it, it is there.