for the money the logitech's are hard to beat, the quality isnt that great, but they work well for desktop speakers.
I just bought some, I forget the model now, but they are 5.1 but without the built in decoder... I have them plugged into my airport express for air-tunes action.
the subwoofer is under my desk, I have it turned the WHOLE way down, no kidding, it's boomy, even at it's very lowest level, I find it still too boomy, perhaps I should move the sub somewhere else.
It's obvious they are targetting gaming and techno weenies that love the 'boom'.
I had the top of the line ones a few years ago.. the Z680's or something? Out of the box the subwoofer had a rattle in it, it went back, the next set also had a rattle. in the end i was in the shop i bought them from, going through every set they had on the floor, testing them, every set had a rattle in the sub, I got a refund.
But yer, for the money you spend, they work well for some regular listening, etc.