To ensure your download hasn't been tampered with, verify it against official SHA-1 hashes. For example, the English Vista x64 with SP2 (All Editions) typically has a hash of AAEE3C04533899F9F8C4AE0C4250EF5FAFBE29A3 . System Requirements for 64-bit Vista

: This allows the 64-bit OS to run almost all 32-bit applications natively, giving you the best of both worlds—modern memory capacity with legacy app support.

Locating a today is primarily a task for enthusiasts, retro gamers, or those maintaining legacy hardware. While Microsoft officially ended support for Windows Vista on April 11, 2017, the 64-bit version remains a landmark for being the first Windows OS to push 64-bit computing into the mainstream. Where to Find Windows Vista 64-bit ISOs

Are you planning to install this on or as a virtual machine ?