Hrm. What is the fastest wired network I can get?
The fastest network you could get would be 10 gigabit. You don't want one though because the interface cards would cost as much as the rest of the computer, in many cases.
The suggested gigabit network that was suggested is appropriate. I should point out that you need NICs (Network Interface Cards) and at least one switch to support them. If your primary network usage is video, strictly speaking, only the server and the switch need to be gigabit devices. The playback computers could be 100 Mb, as are most of the extender type devices (PS3 supports gigabit, however).
Gigabit interfaces are cheap, so there is little reason to scrimp on them. Further, if you anticipate heavy usage (more than two simultaneous streams) you might want to look at a server class NIC for the server which might set you back a couple of hundred dollars.
Video playback of material originating on optical discs is about having the data available just when it is needed for display. Unlike streaming protocols which use large buffers to prevent problems when something is a bit late, consumer products never have enough RAM to do this, but can depend on very precisely specified characteristics of the optical drive itself.
When you deliver optical media content from a server over a network, you violate the assumptions of the media authoring tools. To make up for that, you need a network with several times the speed nominally required and storage much faster than the original optical drive to compensate for any lost bits, retried packets or retried reads from the server's disk drives.
Wireless networks generally do not have the spare capacity and have much higher error rates than can be tolerated. In spite of this, some people win every time they roll the dice, but the rest of us need wired connections for HD video.
Ideally, you want all the NICs and the switch to support jumbo packets, packets larger than the 1500 or so bytes that was appropriate for 10Mb ethernet 20 years ago. You must configure the computers to use them or the effort is wasted, however.
Also, are there variables that affect image/sounds quality? Such as graphics cards, sound cards, CPUs, etc...? Could a graphics card have better image quality than a lesser graphics card?
Cards can certainly make a difference. If you have really good viewing equipment, you might be able to see the difference between a $100 card an a $300 card when comparing image quality. Or you might not.
What better cards deliver is often less about the pixels displayed, so much as the degree to which they off-load the CPU. Off-loading the CPU is good because it makes the smoothness of your playback less susceptible to disruption when that network or server skips a beat, or Windows starts scratching itself. Effectively, the CPU can catch-up more quickly and skips can be avoided.
It should be noted here that a great gaming card may only be a good HD playback card. Often, a cheaper card with good video acceleration are better, cooler and, importantly, quieter than the more expensive cards. Nvidia's 7600, 8600 and 9600 cards have followed this pattern. Currently, ATI's cards have gained much favor.
By sound quality, I refer to digital sound without any conversions. So, any differences between sounds cards and transfering pure digital sound? I'm looking at the new Auzentech HDMI encoding card coming out in September.
Digital outputs are all the same if they manage to get the bits from one end to the other without error. Unfortunately, there are errors, which often have more to do with the drivers than any expensive hardware. To work right, digital outputs need not be expensive. But the maker of a more expensive card might spend the money to get it done right in software.
At the other end, analog outputs are susceptible to quality issues where improvements are exponentially expensive. The do, however, avoid some of the stupider DRM issues that can make digital solutions so frustrating.
Right now is a fine time to stand back while the dust settles and the prices moderate. If the money is burning a hole, the Auzentech is probably not a bad choice. They have delivered some good cards for home theater usage and will probably make good on the promise of HDMI...eventually. If tinker and tweak are your thing, get in on it early.
