I have DELL Studio 1557 with an esata port. I'm planning to buy an external drive of 2 TB. I need a high speed transfer drive. Was wondering whether to go with an esata interface or the new USB 3.0, which is going to be used with the USB 2.0 port. I know that if the USB 3.0 drives are supposed to be used with USB 3.0 Host Controller to get the extensive superspeed, but there will be a considerable speed variation, if its used in the USB 2.0 port., tried googling it, couldn't find anything.
It depends on whether you want to pay a premium for futureproofing.
Drives with a USB 3.0 connections are still a bit more expensive, and the USB 3.0 capability won't really benefit you if you plug it into a USB 2.0 port. So today, using eSATA would be best.
But within a year or two USB 3.0 will doubtless become ubiquitous, and some systems you may want to use your drive with (laptops, for example) may not have eSATA ports. For mechanical hard drives USB 3.0 should perform as well as eSATA.