Why don't you explain to him instead of poking him in the chest going, "HA HA!!! I KNOW MORE ABOUT METAL THAN YOU DO!!!!!"
Maybe he's just getting turned on to some of this stuff and he probably wants to name drop a few bands around you to not feel like a total dork. I mean, you gotta admit that metalheads are some pretty nasty and evil bastards. He's a noob...we all were at one time...although I've been listening to heavy metal since I was 5.
Unless he's a complete douchebag, give him a break and introduce some bands to him that you think he might like. Metalcore is a whole lot better starting point than Linkin Park.