My existing storage HDD (where I store my user profile, including music, videos, documents and pictures, and emails) is approaching capacity (1TB WD Caviar Black).  I'm considering moving in the near future to a NAS system, to address a range of issues, and to be able to institute a proper backup system, but for now I just need a new HDD with a larger capacity to store all my stuff.  So I'm looking at buying a 2TB HDD, which I can then use as the basis of a NAS setup in a few months time.

Most of my recent hard drives have been Western Digital, and I haven't had any problems with them so far (touch wood).  But it's been about 3 years since I bought storage, so I'm unsure what to go for.

Pricespy ranks the Seagate ST2000DM001 2TB drive as number 1, and is priced nicely at about $150.  But the 2TB WD Caviar Black is nearly a $100 more expensive.  What's with the price gap?  Is the Seagate rubbish compared to the WD, or is WD now hugely overpriced.  Which of the two would you recommend?