I just got around to trying PV drivers on an XP64 domU with Quadro secondary VGA passthrough. Xen 4.2.2 PV drivers 11.0.356 signed Quadro x000 series cards as secondary Good news - it works just fine. Better news - holy crap! The speed! I can now actually tell that the domU disk is backed by an SSD! Enabling anti-virus in domU might actually become a workable proposition now. Gordan