All about gaming

Hi to all experts out there, I have some doubts that I hope any help & advise will be valuable to me. I am helping my nephew on his gaming needs. What does it takes to built a robust gaming PC?
Is AMD or Intel PC most prefer for gaming? Apparently, AMD got heated out easily & you need some sort of water to be installed inside the system for cooling effect. Is that true? What kind of video card is recommended? My nephew is playing World of Warcraft and he is looking into building a system this weekend. Appreciate for any suggestions..