Yeah, Macs don't have anything that even come close to your PC.
If his Mac has a core 2 duo, it's laughably out of date already, and a PC with the same performance would have cost $400 total.
Any AAA game from the last few years (Metro LL, Crysis 3, Witcher 2, Far Cry 3, Borderlands 2, Battlefield 4, Dead Space 3, Thief, Assassin's Creed III, etc) would show that your PC is many times stronger.
The only part where his rig might be superior is the screen/monitor, since Apple usually uses high quality 8-bit IPS panels.