Windows 2000 Professional / Server, Windows XP Home / Professional, Windows Vista and Windows 7 have a nifty little feature called write caching buried within the depths of property tabs. Normally, this type of feature is used with SCSI drives in server applications to provide greater data integrity.
When drives employ write-back cache, any interruption of power to the drive or system may cause lost or corrupted data because the drive does not have time to write the cached data to the disk before the power is lost. However, when write cache is turned off, drive performance slows down.
Additionally for external hard drives, choose "Optimize for Quick Removal" in the Policies tab in Windows Vista and XP, or un-check the "Write Cache Enable" box in the Disk Properties tab in Windows 2000, which amounts to the same thing and can help prevent corrupt partitions or data loss due to an unexpected external hard drive disconnection.
The default for this feature is checked or enabled. If you need to slow your hard drive down to resolve issues such as timing problems, have ongoing unexpected system shutdowns or disconnections due to power outages or other, it is recommended that you disable the write-caching feature.