Google Chrome 37 has been promoted to the stable channel, which also brings the first 64-bit version of the browser to wide availability. Microsoft has had a 64-bit version of Internet Explorer for a while on 64-bit versions of Windows but Firefox and Chrome have remained with the 32-bit architecture up to this point. Some might have previously downloaded Waterfox or Minefield, 64-bit versions of Firefox.
Why would you want to go with a 64-bit version of Chrome? As they explain in the Chromium blog, you see numerous improvements:
64-bit Chrome offers many benefits for speed, stability and security. Our measurements have shown that the native 64-bit version of Chrome has improved speed on many of our graphics and media benchmarks. For example, the VP9 codec that’s used in High Definition YouTube videos shows a 15% improvement in decoding performance. Stability measurements from people opted into our Canary, Dev and Beta 64-bit channels confirm that 64-bit rendering engines are almost twice as stable as 32-bit engines when handling typical web content. Finally, on 64-bit, our defense in depth security mitigations such as Partition Alloc are able to far more effectively defend against vulnerabilities that rely on controlling the memory layout of objects.
To download the 64-bit Chrome, it is opt-in. Your 32-bit Chrome on a 64-bit Windows will not automatically update to a 64-bit version of the browser. Instead, you will have to manually download it from a Windows 64 platform page. There does not appear to be a 64-bit all users version of Chrome available for download yet nor a Chrome for Business version.
The only downside noted with the 64-bit version of Chrome deals with plugins. You may have to install a 64-bit version of Java and Silverlight to go along with your updated Chrome but they are both noted as working properly. Google Earth and Google Voice however will not work since they are 32-bit plugins. Chrome plans on dropping support for NPAPI plugins in coming months anyways.