While QCOW2 is native to QEMU, it is compatible with other popular virtualization software:
Search for: "Windows Vista Qcow2"
While not a direct Qcow2 source, TechBench provides untouched Vista ISOs. You can convert these to Qcow2 using:
If you want to run in a Linux-based virtual machine (VM), a pre-built QCOW2 image saves you from a manual installation.
Replace /dev/sda with the disk identifier of your physical machine's hard drive.
: You can find original MSDN ISO files (x86 and x64) including Service Pack 1 and 2.