Welcome to SPCR. Nice to see an appreciative newcomer.
Why the Noctua NH U9B SE2 ? Go for a HS w/ a 12cm or bigger fan. It'll be quieter and cooler.
Your HDD choices are not optimal for noise. Not sure of your criteria, but Seagate drives have lacked Automatic Acoustic Management for years, and as a result generally have the loudest seeks. I know you're choosing 7200rpm drives on the assumption of their higher performance, but if you take a close look at out last few HDD reviews (with the long table of summary data on many drives), the latest 5400 and 5900rpm drives come very close to to the 7200s, and when they have high areal density, often better them. Personally, I can't imagine why you would not go with 2tb WD Greens instead. Then you'd need fewer drives and the performance is very good.
I would also consider getting a biggish reliable SSD for the OS. With a new build, and the CPU/mobo/RAM you're going for, it will make a night/day difference. (I speak from recent personal experience, having moved from a 3-yr old C2D E8500 w/WD Velociraptor 300 and 4gb RAM to a new main PC w/ Intel 2600K, Asus P67Pro board, and 8gb of ram with an Intel G2 160gb SSD. Photoshop CS5 now opens & is fully operational in all of 1.5s!) Guaranteed, in your proposed build list, that 500gb Seagate for OS will be the biggest bottleneck. W/ newer Intel SSDs out now, that G2 X25m-160gb in my rig is on the market for around $350. Well worth the $$ for a DAW imo, assuming 160gb is big enough. If you must go to 250gb, an SSD is probably beyond your budget, they run $600+.
As for cases...
Fractal cases are a little tricky. In photos, they look really nice, and their list of features is fantastic. But hands-on, they're disappointing to me. They're made of lighter metal than the older Antecs like Solo 1/2 or P180 series, they flex more, they're overall more cheaply made. For me, from the point of view of an enthusiast who is often in/out of the case, they just don't have enough of a quality/durability feel. Let me put it this way: We don't use any in our lab. They're good cases overall, and very good values, but...
I prefer stronger, heavier, sturdier cases -- like the P183 or Solo2. The NZXT H2 -- http://www.silentpcreview.com/nzxt-h2
-- is also an excellent sturdy case --but it needs the vents opened up to breathe better. That's the case I used for my new build, with the vent openings at the bottom of the front door and around the base enlarged to improve intake. It runs perfectly cool under all the loads I throw at it (including a bit of gaming using a HD6850 video card). The HDD mounting could be better, but with a single WD Green 2tb, I can barely hear the seek chatter w/ the case/system 3' from me on the carpeted floor next to my desk.
For your needs, I'd also consider the Solo2, w/SSD and 2 suspended 2tb or larger drives. When you need more capacity, add an external eSATA box like... an Icy Dock MB561US-4S -- http://www.silentpcreview.com/Silent_Ho ... de/Backups
-- or similar. Put quiet HDDs in it, run a 6' high quality eSATA cable, and set the box on a thick (say 1" or more) soft pad of foam in a nearby closet or closed cabinet (with a vent somewhere not facing you).
NOTE: The captive spring-loaded thumbscrews used on the Solo 1/2 are still my absolute favorite/best side panel securing method ever -- they are head & shoulders over everything else and such a delight if you're in/out of your case a lot.