CentOS - Apr 2012 - virtio or IDE on SBS 2011 (or any domain controller)

CentOS 6.2, using latest KVM drivers for Windows guests. Using LVM for
storage, software raid 10, RAW with write cache disabled in the virt
manager.

When using virtio drivers for disk drives Windows Server complains about
write caching being enabled. I can't disable it either. Using IDE prevents
this from being happening, however the performance sucks. All searches
related to fixing the write cache issue results in it being a controller
setting, bios setting or manufacturer flaw. Since this is all  software
raid, LVM and Red Hat's virtio drivers it doesn't apply (or at least is
fixable by others methods).

My concern is data integrity over performance, but I'd like to know what
others are doing.

My fallback plan is to use IDE for the OS and virtio for the Data drive,
moving Exchange and the folder redirects to the data drive (or even a
different server install attached to the domain), but I'd appreciate others
experiences before I resign to dealing with this limitation.

Thanks,

Jacob