I personally find that gaming and movie watching want two different setups.
I find for gaming over ear headphones offer FAR better immersion than surround sound speakers, but for sitting back watching a movie I like my 7.1 gigaworks S750 setup.
I personally DONT find the 7.1 surround sound anywhere near as immersive for gaming as a pair of good headphones.
If I had to buy today for 5.1 I would choose the Logitech Z-5500, mainly because I would love to finally find a use for those spdif ports .
My current speaker system has been discontinued I believe, after many years on the market, I think it needed it, the sound might be great, it might be decent quality kit, but the lack of connectivity options were becoming a bit of a killer on it... Many times Ive ran into barriers wanting to hook up different kit to it. Quality 7.1 systems can be hard to find which is a shame given that bluray is only just starting to become popular.
For DVD only use 5.1 is all you need, for some blu-ray titles 7.1 is nice. Theoretically for gaming 7.1 is better than 5.1, but I find a good pair of stereo headphones offer a far better gaming experience.