Well I'm building a new gaming computer and this will be my first time. =] If you guys would be kind enough to look over this list and make sure I didn't mess anything up. =p Any questions, comments, or concerns are much appreciated. =] I'm mostly going to be playing WoW on it but I also dabble in some higher-end stuff with my friends. (Such as Crysis and other first-person mutliplayer games)
Look into a different power supply. Three 12V rails with only 18 Amps on each is terrible, especially for multiple video cards. You want single(or at very least double) 12V rails with high Amperage.
I'm not specifically suggesting this, but this is an example of what you want to look for. Two 12V rails with a very high 40 Amps running through both.