[libvirt-users] IDE vs SATA vs VirtIO

ok from googling its clear that VirtIO is consistently recommend for the best performance. However, with some legacy VMs that we are bringing into the system isn't an option. Is there a peformance difference between IDE and SATA? For that matter how much BETTER is VirtIO over the other two? Note, these are QCOW2 images if that makes a difference. -bill