More reliable hard drives that use less power are set to hit the shelves by early 2011 -- but Windows XP users beware.

The modern drives will use an "advanced format" that changes how they store data; manufacturers are calling it one of the biggest format shifts in 30 years.

These next-generation drives will store data in 4-kilobyte sectors, a substantially larger size than the 512 byte sectors used in older drives. The smaller sector size was useful when drives held far less data than today's massive-capacity platters, but having tens of thousands of sectors in a gigabyte or even terabyte drive wastes space.

But Window XP users who swap an old drive for the changed format may face problems, the BBC reports, in the form of a 10% speed hit.

To help Windows XP cope, the advanced-format drives will be able to pretend they still use sectors 512 bytes in size. An awareness campaign is planned to warn about the problems these drives could inflict on Windows XP, which was released well before the 4K format was decided on.

The International Disk Drive Equipment and Materials Association says it is nonetheless committed to adopting the new format by 2011, which experts believe will make drives about 7-11% more efficient -- at least in newer operating systems.

Click here to read the full report from the BBC.