Couple of other hints--the amp rating you want to achieve and length of the run has an effect on the gauge of wire you use. For example, if you are using a 20 amp breaker (in order to acheive a 20 amp circuit), you need to use a heavier guage wire than standard romex. And if it's an unusually long run, an even heavier gauge still. Head to your local home store and browse a DIY book on electrical circuits--they generally have a listing of NEC tables (National Electrical Code) that you can reference.
BTW, I ran dedicated 20A circuits to both my reference rig and my home theater, and there is huge upside. I didn't go for any of the exotic materials, basically because of the 80/20 rule. I was able to get huge gains (80% improvement) by just getting the dedicated circuit in place at a low cost--standard 12/2 romex and hubbel outlets (at 20% of the cost).
BTW, I ran dedicated 20A circuits to both my reference rig and my home theater, and there is huge upside. I didn't go for any of the exotic materials, basically because of the 80/20 rule. I was able to get huge gains (80% improvement) by just getting the dedicated circuit in place at a low cost--standard 12/2 romex and hubbel outlets (at 20% of the cost).