Well for the system to be truly responsive you'll want an SSD. Prices on those are definitely plummeting. You can get a 512GB Crucial for about $400 if you need space. Of if you don't mind dropping down in capacity for your primary drive and then having a secondary drive for all your storage, you can get most 120 and 128GB for $130 or less.
Unless you absolutely must have a large boot drive, I'd go for a 120 or 128GB SSD, and then use that 1TB WD Black for all of your data. Most programs should fit on the SSD, larger ones just install to the 1TB. Keep your data on that 1TB as well.
Otherwise the system looks pretty solid.