I heard good things about Hallowmere , a series starting with In the Serpent's Coils by Tiffany Trent.

But...maybe I've been reading too much of this style of fiction or something, but I found myself a little bored with the "schoolgirl surrounded by unknown forces and bullies finding out she's special" kind of thing. And I just read one kind of like this, only it was done a little better, I think.

I felt like the author's twist (wherein the bad guys were revealed to be good, etc) set up this thing where we never got to know those characters very well, and thus I felt distanced from the story. Everything was a bit too mysterious, maybe.

And I found myself skimming a lot of the school bullying parts.

So I guess I don't recommend this one as highly as some of the others I've been reading recently, but if you like boarding school magical stories, this one might be up your alley.