I'm a 7.1 user for over a decade.
I've been using them with computer for a long time. I had purchased a PCI Soundcard, the
Creative SoundBlaster Audigy 2 ZS Platinum Pro [still have it and might sell it if anyone is interested] which was a 7.1 beast
I had also purchased
Creative Inspire T7700 7.1 Speaker System which went extremely well with the setup!
All my games and movies ran at 7.1 surround. The amazing thing was, the soundcard could upmix to 7.1 if the source did not support it.
I kept using that system until last year when i built my new PC. Sadly the motherboard I got did not have the PCI slot and therefore I had to ditch my old card
. However, the built in soundcard did support 7.1 audio but I couldnt connect my xbox or other audio sources to it like I could with my Audigy 2 ZS Plat Pro. The quality of that card still outblows anything that you get with the motherboard.
Unfortunately, Creative no longer makes 7.1 soundcards, all their new lineup is 5.1 which is odd since every game supports 7.1 (PCM format). I had no choice but to move onto something big, such as my recently purchased Onkyo HT-S5600 7.1 HomeTheater system.
I absolutely love it! However when I was setting it up, I thought it would blow me away... yet I was mildly amused. Why? Heck the soundsystem is awesome, dont get be wrong there... it's just that I had under estimated how good my creative speakers actually were. Since I've been listening to them for almost a decade - the change to a bigger speaker system didnt give me that punch. It wasnt a breath of fresh air, just a little better. The onkyo obviously sounds great... its spectacular but man, the creative speaker can really put up a fight against these big boys
In short - if you can get a hand on the creative 7.1 system then dont hesitate in picking them up [I would sell you mine but my friend already took mine and connected to her LED]. I do however have the soundcard if anyone is interested.
As for the movies. All movies support 5.1. If you get blurays or download prints with uncompressed audio such as DTS-HD. They can give discrete 6.1/7.1 where supported. But have no fear, the soundsystem (HT or computer soundcards) are capable of upmixing 5.1/6.1 to 7.1 easily.
As for the Onkyo 4505 - dont go for it... look for the 5600 - there is a huge difference in them.