If you can't find a pre-made QCOW2 you trust, it is safer to build your own from a "Lite" ISO using QEMU : Windows 7 Super-Nano Lite : blzos - Internet Archive
The query windows 7 lite qcow2 best is common among virtualization enthusiasts, retro computing fans, and low-resource users who want a stripped-down Windows 7 VM that boots fast and consumes minimal RAM/disk space.
qemu-img convert -O qcow2 -c w7lite-base.qcow2 w7lite-final.qcow2
: The file size on your physical drive only grows as data is added to the virtual disk, rather than taking up the full 40GB+ immediately.
Virtualization enthusiasts prefer the QCOW2 format for several key reasons: