Download the latest version (7.0 or newer) from virtualbox.org . Install the as well for USB 2.0/3.0 support.
If you choose to install from an ISO, follow these steps to ensure the 64-bit version runs correctly: How To Install Windows XP In Virtual Box 2025/2026
No. You must perform a clean installation. 32-bit to 64-bit upgrades are not supported by Microsoft.
Since Microsoft has discontinued official downloads, you must source the installation media from community archives or physical discs.