Pentium - Celeron or AMD? Need advices please

Hello, i have a friend that wants to buy a computer. That computer will be used mainly to play games, consult internet, watch some videos, and some other stuff. No video editing, image editing, no Flash. Just a PC for a normal guy with two kids.

What do u advice? In terms of the processor? Pentium - Celeron - or AMD.

In my honest opinion i had advice him on a Celeron or AMD cause they are cheaper. However a fnother friend of him told hin that i was crazy cause celerons suck. What arguments can i use to convince him he is wrong?