Qubes: security by virtualization

The only thing that disturbs me here is the requirement for VT-d support for networking. IIRC, VT-d requires a modicum of BIOS and chipset support, and I have never yet seen a single desktop on which this support works. Sometimes turning it on does nothing; sometimes it locks up the system as soon as you try to use it, possibly because it's buggy as hell and DMAs stuff into the wrong places. I've seen it working on server systems, but isn't this supposed to be a desktop OS?

(maybe it works on very recent systems; the most recent I've tried it on is Nov-2009 Asus motherboards, which fail. Maybe Intel motherboards are more reliable in this area.)