Ugh, this sounds like it's so awkward for you! If you're sure you're not interested, maybe you should type him another message telling him that he's not your type? You could always say that you're not looking to date right now, but I have a feeling (given that he's being so forward already) that he will just continue to pursue you, thinking "ooh, maybe she's ready to date now, I better check in with her!" or whatever.
Well, I don't think it is weird at all, but he probably is not going to give up until you are firm with him, almost to the point of being rude. Try telling him that you are just not interested. This is much easier to do in writing (via MySpace) than in person. Good luck.
Ick! The problem with things like that in high school is that, well, it's high school. Boys aren't mature enough to handle the truth (you just aren't interested) without making a big stink - at least in my experience.
If I were you, I'd just be polite. I'd respond ro a few of his emails but just politely and shortly. And if he asks you out, just say no thank you. He'll get the hint eventually.