There is no real difference between single and multi rail. Get whichever you can afford. Lots of people like modular, I still prefer the wired kind. I don't have to worry about loose connectors, or inserting into the wrong port. (or which goes where again?) Put your DVD drive in the second from the top bay, and ziptie/twisttie the extra hardwires and shove above the DVD drive. Looks nearly as neat, and no wire issues.