Solid-state drives offer a considerable performance advantage over hard drives, but they cost a lot more. Replacing a MacBook Pro's hard drive with a similar-capacity SSD could cost as much as the notebook, while a smaller, more affordable model might leave you short of storage space.

Hybrid drives such as Seagate's Momentus XT are designed to resolve this dilemma. By combining a large solid-state memory cache with a regular hard drive, it offers a performance close to that of an SSD at a cost-per-GB that's more like a HDD.

This second-generation Momentus XT is 750GB instead of the original Momentus XT 500GB, and the non-volatile cache is expanded to 8GB, up from 4GB. The SATA bus is now 6Gbps, and the hard drive speed remains at 7,200rpm.

A bootable image resides on the flash memory, giving it much faster start-up times than a standard hard drive. In our tests, booting a clean Lion install on a 2011 MacBook Pro took less than 26 seconds, compared to 39 seconds using its factory-installed hard drive.

The hybrid's random read/write scores of 20.433/47.228MB/s roundly trounced the original hard drive's 17.202/16.046MB/s too.

If you want to boost performance without sacrificing storage, a hybrid's the way to go. The Momentus XT is fast, capacious and value for money.

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