I'm thinking of getting a ! to 2 Terabyte external USB drive for storage and back ups. My PC is pretty fast and has lots of RAM, etc. The only problem is that when I bought the internal D drive, I never thought I would fill the 275 GB with data. So I want to move non-essential data to the external. The only thing I'm not clear on is whether to go with USB 2 or USB 3. I understand I can utilize either with and add-in card. Given my usage plans, will USB 3 have any significant advantages over USB 2? Enough to justify the extra cost? Any drawbacks?