What is a "sample rate?"

Its essentially how many times an audio stream sends out data over a set period of time.

Its kinda the audio equivalent of Frames per Second. The more you have, the smoother the transition from one frame to the next. A higher number of frames gives a smoother experiance.

As such, a 192Khz Sample Rate samples [or more simply, outputs] data from an audio stream more often, giving a more accurate audio playback.

http://en.wikipedia.org/wiki/Sampling_rate

The graph kinda shows how it works; the more often you sample, the more exact the audio output will be.

It is worth noting, if the audio source is sampled at "X" sample rate, and your are outputting at "2X" sample rate, you won't get any real increase in quality.

And its worth noting, only a few cards support 192KHz output for the PC [and even then, thats normally limited to the front outputs]. I don't think any Creative card supports 24-bit, 192Khz yet either...

I went into the sound controls in windows control panel, and I believe my X-Fi Fatal1ty Titanium card does support 192KHz 24-bit audio, because it is a selectable option.

I currently have it set to 96KHz

How would particularly PC games benefit from high sample rates?

http://www.youtube.com/watch?v=zC5KFnSUPNo&feature=rela...

That is the highest sample rate it will handle, most games dont support audio tracks with that bit rate so you are restricted to the lowest sample rate in the system. Since human hearing only has a range of 20 Hz to 20 kHz a sample rate of 48 kHz is reasonably common as its sampled often enough to not lose higher frequencies.

Higher sampling rates lead to slightly better quality sound(if the source and the card and the speakers hooked up are all capable of replicating it properly) at the expense of more processing needing to be done, if you cannot hear the difference between 96 kHz and 192 kHz sample rates then you are a normal person and it really doesnt matter, most people wouldnt notice any difference at all between a 48 kHz sample rate and 192 kHz because 48 kHz already covers all frequencies in the normal range of hearing.

Rates at 192khz and sometimes even 96 can cause audio problems like crackling in games. I have an M Audio for production and I have to turn it down for gaming.

There is no such thing as a sample rate that is too high, any crackling or distortion is either caused by the DAC being of lower quality or a wiring/speaker issue, it is not directly related to the sample rate.