Seagate's BlackArmor PS110 USB3 drive kit brings USB3 to laptops without USB3. And your transfer speeds will be 3 times what they were through USB2. If you weren't excited about USB3 before, you should be.
The Price

The Verdict

It's three times faster than USB2, which is a pretty good jump this early on in the life of the standard. In theory, you can get somewhere around ten times as fast, but you're then running into bottlenecks such as the actual drive itself and the computer you're transferring data to. But our biggest complaint is it's not OS X compatible.
Here's how we tested. The kit comes with an ExpressCard adapter that can drive any one USB3 port. However, the adapter does need to be plugged into a USB2 port for supplementary power. So we used a MacBook Pro (an older one with ExpressCard) booted into Windows 7 to test. We also used a CyberPower P55 tower with USB3, because we wanted a more powerful unit to make sure the bottleneck wasn't with the computer we were using. And we went with CyberPower, because they're one of the only OEMs now that are including USB3 on most (all) of their builds.
Here's CyberPower's test results first. Comparing the USB3 drive to a similar Seagate USB2 drive showed that direct transfer rates on big files are about 3 times faster. A bunch of smaller files evened up the match, since that's more dependent on the hard drive itself to seek the files rather than the actual data transfer. Even still, USB3 came out ahead.
Similar results came out when we tested on a MacBook Pro bootcamped to Windows 7, because the ExpressCard kit doesn't support OS X. The difference between USB3 and USB2 is less pronounced here—not quite twice as fast—because of the bottleneck with the machine, rather than the transfer. But it is faster, which is great if you're constantly moving large files around on the go.

Beyond the fact that the kit doesn't support OS X at all, Seagate also brilliantly placed the drivers for the ExpressCard adapter on the USB3 drive itself. This is somewhat confusing, because they don't tell you that you don't have to use the adapter to access the data—you can plug the drive into a USB2 port, get the drivers off, install it, then plug the adapter in.
It's a good drive

This USB3 drive costs a little extra from Seagate, since the 1TB version of their USB2 drive goes for $150, and this is $170 with just 500GB, but does come with an ExpressCard adapter. But if you plan on getting a USB3-capable laptop (everyone will), you might as well future-proof yourself now. And if you're looking for a USB3-compatible PC, there's CyberPower, which has them on just about all their systems now. [Seagate, CyberPOwer]

Comes with an ExpressCard kit

ExpressCard kit needs a extra USB2 slot to power

Slightly pricey

Doesn't work with OS X

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