Don’t try Vista 64-bit on underpowered hardware. Minimum recommended:
Released in 2007, Windows Vista was the first Windows version where 64-bit (x64) computing became a mainstream consideration for home users. While 32-bit systems are limited to roughly 3.5 GB of usable RAM, the 64-bit editions of Vista dramatically expanded memory support: 8 GB Home Premium: 16 GB Business, Enterprise, & Ultimate: 128+ GB System Requirements for 64-Bit Vista windows vista 64 bits iso
Microsoft no longer provides direct official downloads for Windows Vista ISOs on its primary consumer site. However, there are a few reliable avenues for obtaining a legitimate copy: Don’t try Vista 64-bit on underpowered hardware