The notebook is an ASUS N56D.
Right now the battery isn't charging but it's not dead. I tried removing the adapter and running the computer exclusively off the adapter and it wouldn't start, so I'm pretty sure it's the adapter gone bad and not anything internal (I hope) since the adapter isn't getting warm when plugged in (am I assuming correctly there?).
I've been poking around and i seems difficult to find an OEM that is legitimate (at least going by reviews) and it's also difficult to find a third-party adapter that's got decent reviews either.
I'm sure I'm just being dense about this, but better to ask and look stupid so long as I get an answer.
I'll probably just take it to the local guy my brother bought it from tommorrow and ask if he has any replacements handy, though I'm sure it'll end up being more expensive than if I bought it myself and I'll have to wait for it to come in to his store anyway.