Pure gaming Microsoft is ahead and always will be.
I dont use macs, they've always cost more and done less only people i know that use them are either abit of a poser or have little interest in technical things.
Dell customer support sucks pretty much 60% of the people working at dell are morons. But then i have heard many bad things about Mac CS too, the thing i like about dell is i feel no guilt when milking my CC warranty ;P.
But macs never seem to go wrong, though i am never sure there ever working right either, having to be the tech for the few macs, i wouldnt feel happy a computer that after a scans says everything "appears" to be ok, lol.
But i wouldnt advocate mac or PC its about what you need, how you use it, what you like and how much money you have everything has a place, and when i saw my mums new mac lappy i had to sneak off for 5 mins and rub my self against it, very sexy machine, gonna try stuffing the contents of my 1710 inside that case lol