Building/Buying a good desktop

[noname219]

So, my laptop is taking his last breath (and I might lose everything in the process), I need another PC soon. I'm not sure if I should buy one or build one, it might depend on the price. My budget for the computer is between 2,000-3,000 $. I will mostly do design work, that means a good video card and a shitload of ram - basically, performance. I want something that lasts for a while too.

Since it would be my first build, I'm not sure what I should be aware of, so that's where I need your help. I went to pcpartpicker.com and try to build something out of thin air, this is where I'm at :

For the parts, refer to http://ca.pcpartpicker.com/user/noname219/saved/4G4g
(keep in mind that I'm not building a gaming desktop, I'll mostly use it for design stuff)

A few notes
Storage : 2TB for the hard drive is enough for me, I just bought a brand new external drive for my backups, Seagate 2TB.
Operating system : Windows 8.1 is more capable than Windows 7, and since I don't hate it…
Monitor : I might add a second one someday
Mice : already have one, Logitech Performance MX
Keyboard : I don't play really rhythm games anymore, but I'll probably go for a mechanical keyboard (will look for that thread on the forums)
…more in the following posts that I don't want to add here