As a side note, I’m editing with ESATA II and premiere is dragging on my Dell M90. But only when I edit externally.. it works fine off the internal drive. Standard DV has rate of 5 MPS, and I’ve heard of several editors streaming to, capturing to, and editing from USB 2.0 Drives. I would also try defragging both your Drive where premiere is loaded and your USB drive. There are other issues you may have to look at beyond that but that’s a good first step.. however what’s NOT a good first step is replacing an expensive piece of hardware based on a hasty conclusion with little or no exploration.