A reader wrote to us asking how to install Microsoft Windows 7 on an additional partition of his Windows XP PC, access all data from both operating systems, and then delete XP without losing anything. Unfortunately, as our Helproom Expert explains, it's not that simple.

QUESTION I upgraded my Windows XP PC with a pair of one-terabyte (1TB) WD ‘Advanced Format’ Caviar Green drives. I’ve applied a jumper across pins 7 to 8 on both drives. I’d like to install Windows 7 on a partition I will create on the C drive, and when I’m sure that everything’s okay I’ll uninstall XP. Until then, I want to retain the data on both drives. I’m confused about how to go about this. Please help. David Bennett

HELPROOM ANSWER Advanced Format drives store files more efficiently by using larger data sectors with fewer redundant gaps between them. However, only recent operating systems natively support the format. Windows XP doesn’t support Advanced Format, so extra steps need to be taken to ensure you don’t lose system performance.

The jumper you describe configures the drive for use by Windows XP, but only as a single partition – you won’t be able to install Windows 7 on a second partition in this format. However, removal of the jumper will result in the loss of all data stored on the drive. This must stay in place until you’re ready to reformat the drive.

Perhaps because of situations such as yours, and the associated risk of data loss if the jumper is removed, WD no longer uses this system on its Advanced Format drives. Instead, it provides a utility called WD Align that ensures disk partitions are stored in a way that lines up exactly with the new larger-sized sectors. If partitions are not aligned, data can straddle multiple disk sectors instead of residing entirely within one, causing the drive to do a lot more work when writing files.

Your only option for now is to install Windows 7 on the second drive, then choose which operating system you want to boot into at startup.

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