Theoretically, USB 3.0 will turbocharge throughput speeds for any external hard drive with a USB connection.

Will it really do that?

Probably not!  The 10-fold  performance improvementpromised most likely won’t be possible unless you have the latest SATA 3.0 or an SSD hard drive. According to several manufacturer’s their devices can’t reach the theoretical 10 fold increase because even with a special PCI or card bus card, they are only reaching 3 to 3.5 times speed increases for 3.5 inch drives used in external enclosures.

The 10 fold speed increases will only be reachable using the SATA 3.0 architecture. The new interface cards should be able to deliver the same speed increase for all USB drives regardless of who manufactured it. That means they will be universal drivers that will work with all USB storage devices and that is good news.

However, the new devices will be slowed down by  several other components in the computer, especially because most laptops typically use slower internal hard drives. Desktops that can install the faster PCI Express cards will see greater speed improvements.

Conclusion

A 2 to 3.5 times speed increase, while not phenomenal, in still a good thing, but unless you really need faster bulk transfer speeds, you will probably be better off to wait until better drivers and chipsets are available for desktops and until the next generation of laptops is released with built in USB 3.0 ports.