what is SATA 6 Gbps? i was looking at techpowerup.com's review of the OCZ Vertex 4 (http://www.techpowerup.com/reviews/OCZ/Vertex_4_256_GB/11.html) and it said that it is needed to preform best. where can i get this? also should i get the 128gb version of this or the 256gb version for gaming? Thanks!!