DarkSable - The Samsung 840 Pro SATA 3 6Gb/s ssd is brand new. In fact, today is the official release date. Although I am confident it will be an excellent ssd it does not yet have a proven track record like the Samsung 830. As usual, I recommend waiting 6 months before purchasing to see if any problems develop.
Denis54 - If you do decide to purchase a new ssd, the Samsung 830 is the drive I recommend. It has a stellar track record for performance and reliability. There have been some excellent sales lately.