This version is widely considered the most stable, ad-free, and lightweight version for older hardware. It supports both 32-bit and 64-bit Windows architectures, including Vista.
Since the official uTorrent download page typically pushes the newest version (which may sometimes have issues with expired security certificates on Vista), legacy repositories are often used: download utorrent windows vista 64 bit
Recent builds like 3.5.5 or 3.6.4 often list Windows Vista as a compatible platform. This version is widely considered the most stable,
While Windows Vista is no longer officially supported by Microsoft, you can still download and run on Windows Vista 64-bit systems using specific versions designed for legacy compatibility. Compatible uTorrent Versions for Vista 64-bit While Windows Vista is no longer officially supported
Even though Windows Vista is an older operating system, several versions of uTorrent remain functional:
uTorrent 2.2.1 Build 25302 : BitTorrent Inc. - Internet Archive
These historic versions were the first to provide "full support" for the then-new Windows Vista interface and networking protocols. Where to Download