While formats like RAW are sometimes slightly faster, is preferred for Windows XP virtualization due to several key benefits:
Windows XP QCOW2 image is a virtual hard disk file designed primarily for use with the Windows Xp Qcow2
Note: Windows XP with updates rarely exceeds 5GB. Allocating 8GB is safe. For legacy apps, 20GB is overkill but acceptable if your storage is large. While formats like RAW are sometimes slightly faster,