You're in a really bad situation, because she doesn't know who you are and you don't even go to her school anymore.
Pass this one up.
On AIM though, there are situations where it has done a lot of good to me. At least around where I live, people will talk to just about anyone on AIM if they're both in high school. I had one girlfriend from another school who's friends all started talking to me over AIM...when my and her broke up i ended up hooking up with two of them after talking to them only online (having either never meeting them in real life before, or having only had talked to them once or twice in person). One of them turned into a LTR of six months.
I'm not arguing that AIM is some sort of pimpin' tool, but there are certain situations where it can be applied...I only talk to people on it who i don't see otherwise (friends out of state, girls from other schools, and my close buddies from my school...who i guess i do see everyday). The key is not to always be on (or have an away message up most of the time - the key here is to HAVE A LIFE, don't sit around waiting for girls to get online) And try to set up actual dates as soon as you can...don't become some random creepy guy who she can't even remember how she started talking to.
With the way society's going, people in high school use AIM ALL THE TIME. It's how most people around here get in contact with eachother to set up plans, get help with homework, whatever.
Also have a little experience before trying to go to AIM...if you're just beginning this whole DJ thing, i wouldn't suggest trying to seduce online, because since you don't know what you're doing, it won't work. Real experience is ALWAYS better. All in all though, i don't think us HS DJs should completely deny AIM any use.