I have a samsung RF711 Laptop and would like to purchase an additional internal drive to use in the spare bay but am not sure if I should buy a SATA 1, 2 or 3 as I'm not sure what will give the best or correct product to use with that model. Can you advise. Many thanks in advance.
The standards are forward/backward compatible and for HDDs. SATA II is adequate, as HDDs do not saturate the connection to make SATA III useful. Therefore, I would just get a SATA II (or III if same price) drive of the capacity you want. It uses a standard 9.5mm height drive like this one, or any similar: http://www.seagate.com/files/staticfiles/support/docs/s...
You might also consider an SSD in the main bay and moving your HDD to the spare slot, which would give you an incredible performance increase.