I had the same message , i think once you run "optimise Disk" with Bootvis it auto enables it
Expanding on APK
To enable or disable disk write caching:
Right-click My Computer , and then click Properties .
Click the Hardware tab.
Click Device Manager .
Click the plus sign (+) next to the Disk Drives branch to expand it.
Right-click the drive on which you want to enable or disable disk write caching, and then click Properties .
Click the Disk Properties tab.
Click to select or clear the Write Cache Enabled check box as appropriate.
Click OK .
NOTE : Enabling write caching generates the following warning. This is normal:
By enabling write caching, file system corruption and/or data loss could occur if the machine experiences a power, device or system failure and cannot be shutdown properly.
Disabling write caching means that, instead of saving up changes for a file on a removable storage device and then doing a bulk write, Windows XP writes changes to the file as the changes are made. This keeps data on removable storage devices more current, mitigating the likelihood of data loss. However, disabling write caching also has a performance impact. Therefore, for IEEE 1394 hard disk drives, Windows applies a special case for the default caching policy by not disabling write caching for these devices.
The basic way to think of write caching policy is:
If write caching is disabled by default, the storage device in question is optimized for safe surprise removal. This is the appropriate action for slower, consumer-oriented storage devices such as flash-type memory.
If write caching is enabled by default, the storage device in question is optimized for performance. This is the appropriate action for high-performance storage such as SCSI and IEEE 1394 hard disk drives.
Note that caching policy defaults for a given device can be changed in Device Manager.
Optimizing the Default Caching Policy
As noted earlier, in Windows XP Beta 2, IEEE 1394 hard disk drives have write caching enabled by default, to optimize for performance rather than for safe surprise removal. This also means users should first stop IEEE 1394 hard disk drives using the hotplug applet before removing them. However, the Beta 2 mechanism for special-casing IEEE 1394 hard disk drives requires additional refinement.
In Beta 2, Windows XP applied the special case based on a list of known device IDs for IEEE 1394 hard disk drives. Therefore, any IEEE 1394 hard disk drive unknown to Windows XP Beta 2 will not be special cased. To improve this implementation after Beta 2, the Windows team is working with the IEEE 1394 and USB standards bodies to develop a mechanism for vendors to communicate to the operating system the preferred caching policy for a given storage device. There is also a method for vendors to enable write caching via an INF file.