35 megabytes a second is pretty respectable for a hard drive's sustained transfer rate. Remember that USB tops out at 60 megabytes a second, so it's not hard to imagine roughly the same transfer speeds in a sustained transfer scenario. Where SATA will help is with bursts - but how helpful that's going to be is debatable, especially if your hard drive has a smaller cache.
IOW, I'm not sure your performance is that bad.