write cache (win/Storage)

According to technet the option to "enable write cache" in the policies
window (w2k3) always has an impact on the setting of the underlying
storage, no matter if it's a single dumb sata disk or a high-end
storage-subsystem with integrated RAID-controller.
I do understand that this setting always implies windows S caching.
is it a driver's setting?
All tests I did confirmed that behaviour regarding IBM DS4700 storage.
When you tick the option the IBM storage manager shows an altered
setting as well. So obviously SCSI commands trigger the setting on the DS.
If hard disk caching is disabled, performance drops to 15% (SATA, duh).
Now I want to DISABLE windows S caching completely, but leave caching
on for the underlying storage.
Would that sound reasonable (and possible)?
Thanks.