[Will]

Well, that's a good enough reason... besides, you never know when you want to build a cappuccino machine into your case...

Something that I didn't see on your list, though, is a UPS. Since you're investing a lot in this already, it would be a good idea to invest a little bit more so it doesn't go up in a poof of magic smoke if you're hit with a power surge. I got one connected to my monitor and computer, and so far (in 6 months) it's protected from noise 4 times, brown outs twice, and black outs 5 times (they were working on the power around my building a lot a few months back).

Also, for performance, you might want to get a second, smaller/faster hard drive for your system partition. Windows likes to send stuff to the swap file even if you have loads of free RAM still, so having a different drive than the one where all your apps are stored speeds things up a bit more.