We've been waiting for that refresh for a couple of years now, and Western Digital finally tipped its hand in January when it announced the Raptor WD1500. The drive retains the Raptor's 10K-RPM spindle speed and Serial ATA interface, but adds a beefier cache, larger total capacity, and support for Native Command Queuing. Just days later, Western Digital pulled back the curtains on the Raptor X, a version of the WD1500 with a window on the drive's internals. That's right: a hard drive window. The Raptor X shares the WD1500's updated internals, and apart from the better view, it's identical to its enterprise-class counterpart. But how does it perform? We've cornered one in our labs and subjected it to an exhaustive set of synthetic and application tests to find out.