Yuki Kajira is one of my favorite composers ^^
I would definatly suggest the .Hack// series (the series that got me hooked on her music), as well as Tsubasa Chronicles
She also did a number of other series and such
Here's the link that lists all the work she's done
Yuki Kajiura
Noir is one of her older titles, she's tends to just get better as she goes
She really is a musical genius ^^